Exceptional Proff 612

"Dynamic Scoring": Why and How to Include Macroeconomic Effects in Budget Estimates for Legislative Proposals Author(s): DOUGLAS W. ELMENDORF Source: Brookings Papers on Economic Activity, (FALL 2015), pp. 91-133 Published by: Brookings Institution Press Stable URL: https://www.jstor.org/stable/43752169 Accessed: 21-03-2019 01:04 UTC

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DOUGLAS W. ELMENDORF

Brookings Institution'

" Dynamic Scoring": Why and How to

Include Macroeconomic Effects in Budget

Estimates for Legislative Proposals

ABSTRACT Official estimates of the budgetary effects of legislative pro- posals generally include anticipated behavioral responses except for those that would alter overall output or employment. Based on my experience as director of the Congressional Budget Office and on the analysis in this paper,

I conclude that such macroeconomic effects of legislative proposals should be

included in budget estimates - that is, so-called dynamic scoring should be

used - for major (but not minor) proposals and for proposals affecting federal

spending as well as revenues. However, such macroeconomic effects should

not be included when the estimating agencies do not have the tools or time needed to do a careful analysis of those effects. Current rules governing the

official estimating process do not fully meet those conditions.

When gressional legislation Budget is being Office developed (CBO) and in the the staff U.S. of Congress, the Joint Commit- the Con- gressional Budget Office (CBO) and the staff of the Joint Commit- tee on Taxation (JCT) prepare estimates of the effects of that legislation on

the federal budget. Those estimates often play a critical role in congressio- nal deliberations and public discussion.

The estimates produced by CBO and JCT generally incorporate the effects of anticipated behavioral responses to the proposed changes in federal tax or spending policies. For example, estimates for changes in benefit programs include shifts in take-up rates among eligible people, and estimates for changes in income tax rates include shifts in the use of tax deductions. However, by long-standing convention, the estimates

1. The author was working at Brookings when he produced this paper; in January 2016 he became dean of Harvard's John F. Kennedy School of Government.

91

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92 Brookings Papers on Economic Activity, Fall 201 5

have excluded behavioral responses that would have macroeconomic effects, in the sense of altering overall output, employment, or similar variables. For example, CBO and JCT's original estimate of the bud- getary impact of the Affordable Care Act (ACA) included the effects of employers altering the mix of taxable and nontaxable compensation pro- vided to their employees but not the effects of employees altering their supply of labor.

The convention of excluding macroeconomic effects may seem odd from an economics perspective. Estimates for legislative proposals include behavioral responses in order to improve the accuracy of the predicted bud- getary effects and to illuminate noteworthy nonbudgetary effects, and that

rationale appears to apply equally to behavioral responses that affect over- all output and those that do not. Indeed, some analysts and policymakers have argued for years that the estimates produced by CBO and JCT should

include macroeconomic effects - an approach that has become known as "dynamic scoring." However, other analysts and policymakers have argued

in response that including macroeconomic effects would degrade the qual- ity and usefulness of CBO's and JCT's estimates.2 That debate has achieved

greater prominence recently because a rule adopted by the House of Repre- sentatives and the budget resolution approved by the House and the Senate

both call for dynamic scoring in certain circumstances.

Based on my experience as the director of CBO from January 2009 through March 2015, 1 believe the principal concerns expressed about esti-

mating the macroeconomic effects of proposals apply with equal force to other aspects of budget estimates or can be addressed by CBO and JCT. In my view, including macroeconomic effects in budget estimates for certain

legislative proposals would improve the accuracy of those estimates and would provide important information about the proposals' economic effects. Moreover, if certain key conditions were satisfied, those estimates would meet the general goals of the estimating process, namely: that estimates be understandable and resistant to misinterpretation, that they be based on a consistent and credible methodology, that they be produced quickly enough

2. The advantages and disadvantages of dynamic scoring have been considered by numer- ous authors, including Auerbach (1996, 2005), Burman (2006), Committee for a Responsible Federal Budget (2012), CBO (1995, 2002), Furman (2006), Gale (2002), Hassett (2002), Holtz-Eakin and Mandel (2015), Ip (2015), Orszag (2002), and Van de Water and Huang (2014).

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DOUGLAS W. ELMENDORF 93

to serve the legislative process, and that they be prepared using the resources available to CBO and JCT.

Therefore, I conclude that the macroeconomic effects of legislative pro- posals should be included in budget estimates - that is, that dynamic scor- ing should be used - under the following conditions:

- Macroeconomic effects should be included in estimates only for major

proposals, defined as those that would have a large estimated budgetary impact excluding macroeconomic effects, and when estimates of such effects are requested by the chair or ranking member of the House or Sen- ate Budget Committee. CBO and JCT do not have sufficient staff or time

to carefully analyze macroeconomic effects for every proposal under con-

sideration, and using rules of thumb in place of careful analysis risks the credibility of the estimates.

- Macroeconomic effects should be included in estimates for major proposals affecting federal spending as well as revenues. Changes in either spending or revenues can have notable macroeconomic effects, and the estimating process should treat proposals affecting the two sides of the budget as comparably as possible subject to other constraints.

- Macroeconomic effects should not be included in estimates when

CBO and JCT find that they do not have the tools or time needed to do a careful analysis of those effects. That situation will arise most often for proposals that are being developed and amended quickly and for proposals regarding certain types of regulatory policy in which the estimators do not

have significant expertise. Those conditions, and others discussed in this paper, can be readily satis-

fied. However, the current House rule and congressional budget resolution

do not fully meet the specified conditions. The current requirements for dynamic scoring explicitly exclude appropriations bills (which cover about one-third of federal noninterest spending) and give only the chairs but not

the ranking members of key committees the right to request the incorpora- tion of macroeconomic effects in certain estimates. In addition, the thresh-

old budgetary impact for presumptively including macroeconomic effects in estimates is lower than ideal, from my perspective.

There are advantages to an alternative approach in which CBO's and JCT's estimates of macroeconomic effects and their budgetary feedback would be

provided in supplementary reports rather than being included in official budget estimates. In my judgment, though, the advantages of that alter- native approach, as compared with the agencies' current plans for dynamic scoring, are limited and are outweighed by significant disadvantages.

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94 Brookings Papers on Economic Activity , Fall 201 5

I. The Basics of Budget Estimates for Legislative Proposals

CBO and JCT provide the official estimates used by Congress of the effects of legislative proposals on the federal budget. The estimates are based on procedures that have been developed over time and on the professional judgment of the two agencies. The analysts at CBO and JCT stay in their jobs regardless of political shifts in the control of Congress (although the director of CBO and the chief of staff for JCT are chosen by the congressio-

nal leadership), and the organizations have strong reputations for providing

objective, nonpartisan analysis.

I.A. The Mechanics of Estimates

CBO, which began work in 1975, produces public estimates for bills after

they have been approved by congressional committees or before they are voted on by the full House or Senate. For bills that would alter the tax code,

CBO is required by its founding statute to use revenue estimates provided

by JCT, which was created in 1926; for bills that would alter spending poli- cies, CBO uses its own estimates; and for bills that would make changes in both tax and spending policies, the agencies prepare estimates together. The

estimating process is sometimes referred to as "scoring," and the estimates are called "cost estimates." In addition to those public estimates, the agen- cies provide private estimates to members of Congress and their staffers for

proposals that are being developed and have not been released publicly. In a typical year, CBO publishes between 500 and 600 public estimates, and it and JCT give committees thousands of private estimates for legislation under development.

Each estimate shows effects relative to the "baseline," which is CBO's

projection of what would occur in the absence of the proposal. The base- line generally reflects current law, although Congress has specified certain exceptions.

The estimates present changes in nominal cash flows for the current fis- cal year and each of the 10 subsequent years, a period that is often called the "budget window."3 The use of cash flows and a limited time period

3. The principal exception to this statement is estimates for federal credit programs, which are based on the accrual of financial commitments by the federal government (CBO 2012a). All cost estimates exclude changes in federal interest payments that would result from changes in federal borrowing. However, CBO includes changes in interest payments when it provides estimates for overall budget packages, as in its annual analysis of the Presi- dent's budget proposals.

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DOUGLAS W. ELMENDORF 95

mean that estimates do not always measure a proposal's full budgetary effect. Indeed, some proposals deliberately delay cash costs beyond the budget window or accelerate cash receipts into the budget window in order

to lower the apparent budgetary impact.4 However, when Congress is espe- cially interested in a proposal's long-term budgetary effects, the agency tries

to provide information about those effects. And when CBO expects that a major proposal would have notably different budgetary effects beyond the

coming decade than during the decade, the agency can provide information about those effects without a specific request from the Congress.

The estimates are point estimates that are intended to show what is colloquially described as "the middle of the distribution of possible out- comes," but is specifically the mean outcome as judged by the agencies (CBO 1999). Although CBO and JCT are acutely aware of the uncertainty of estimates, the agencies focus on point estimates because the budget process and the procedural rules of the House and Senate rely on point estimates and because measuring the uncertainty of estimates is often espe-

cially difficult.

I.B. Behavioral Responses

CBO's and JCT's estimates generally include the impact of behavioral responses to the proposed changes in law - that is, the estimates are not based on an assumption that the economy is static. For example, estimates of changes in benefit programs include shifts in take-up rates for those ben-

efits among eligible people, and estimates for changes in income tax rates

include shifts in the use of tax deductions. More generally, CBO and JCT try to account for the behavior of households, businesses, federal regula-

tors, and state, local, and foreign governments. However, the agencies do not attempt to predict future changes in federal law. CBO and JCT estimate the magnitude of behavioral responses using a broad range of evidence, including formal statistical analyses done by the agencies themselves and by other researchers as well as anecdotal information from consultations with government agencies and private businesses (CBO 201 1 ; JCT 201 la). The scope of the included behavioral responses varies greatly across esti-

mates. Some potential responses are omitted because the available evidence does not indicate the order of magnitude or even the sign of a response.

4. For example, in a policy change known as "pension smoothing," companies are allowed to defer required payments into pension funds, thereby increasing their reported profits and thus tax payments in the budget window while reducing them later.

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96 Brookings Papers on Economic Activity ; Fall 201 5

Other potential responses are omitted because CBO or JCT do not have the time or resources to collect the available evidence and build and apply

an appropriate model. Still other potential responses are omitted from esti- mates because including the responses would greatly complicate the leg- islative process; for example, the effects that certain changes in spending would have on taxable incomes and thus on revenues are omitted from

estimates because including them would generate jurisdictional conflicts between committees.

In addition, some potential behavioral responses are excluded from esti- mates because the responses would affect overall output, and overall output has been held fixed in cost estimates by long-standing convention. There-

fore, CBO's and JCT's estimates have not included the budgetary effects of changes in labor supply, consumption, saving, productivity, and other aggregate variables. Under dynamic scoring, this convention of "fixed out-

put" would be dropped. The principal exception to this convention before 2015 was the production of estimates for comprehensive immigration leg- islation in 2006, 2007, and 2013. In CBO's view, "assuming that those bills would have had no effect on overall output would have ignored one of

the primary effects of the bills and distorted those estimates too severely" (CBO 2015j).

I.C. Current Status of Dynamic Scoring

In early 2003, the House adopted rule XIII.3. (h)(2), which required JCT to provide an analysis of the macroeconomic impact of all tax legisla- tion approved by the Ways and Means Committee. That rule was adopted again by subsequent Congresses and remained in effect in the House through 2014. JCT (2015a, p. 12) summarized its response to this rule as follows:

For most tax bills, the expected effects were so small that a brief statement to that effect was all that was required. Short qualitative analyses were provided for legislation that JCT macro models were not configured to model. For major tax legislation, JCT staff has provided detailed quantitative analysis of a possible range of effects on GDP, employment, investment, and revenues, based on the results of multiple models using multiple parameter assumptions.

In early 2015, the House modified that rule to require dynamic scoring by CBO and JCT for "major" legislation, defined as legislation that would have significant estimated budgetary effects or was designated as major by the chair of the Budget Committee or the Ways and Means Committee. The rule excludes appropriations bills, requires a qualitative assessment of

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DOUGLAS W. ELMENDORF 97

budgetary impact including macroeconomic effects for 20 years beyond the

10-year budget window, and includes the caveat that the requirements be met "to the extent practicable."

In the spring of 2015, the House and Senate approved a budget resolu- tion that included requirements for dynamic scoring similar to those in the

House rule. Under the budget resolution, CBO and JCT will, to the greatest extent practicable, incorporate the budgetary effects of changes in macro-

economic variables resulting from legislation that has a "gross" budgetary effect of a quarter of a percent of output in any year over the next 10 years,

or is selected for such analysis by the chair of the House or Senate Bud- get Committee. That threshold equals about $45 billion in 2015 and about $70 billion in 2025 based on projected output (CBO 2015a); I address the interpretation of "gross" budgetary effects later in the paper. The resolution

excludes appropriations bills and requires a qualitative assessment regarding the two decades following the budget window.

CBO (2015i) summarized the agency's plans for meeting the require- ments of this budget resolution. In June 2015, in response to a request from

the Senate Budget Committee, CBO and JCT applied dynamic scoring to a proposal to repeal the Affordable Care Act (CBO 2015h). And in August 2015, pursuant to the resolution, JCT applied dynamic scoring to a bill approved by the Senate Finance Committee that would extend for 2 years a number of tax credits, deductions, and exclusions that primarily affect businesses (JCT 2015b; CBO 2015k).

II. CBO's and JCT's Past Estimates of Macroeconomic Effects and Their Budgetary Feedback

The arguments for and against dynamic scoring can be understood best after briefly examining CBO's and JCT's past analysis of proposals' macro- economic effects and their budgetary feedback. Most of that analysis has appeared not in cost estimates - given the conventional exclusion of macro- economic effects from such estimates - but rather in supplemental reports.

U.A. Analytic Approach

CBO (2014d) provided an overview of its methodology for estimating the macroeconomic effects of legislative proposals in a November 2014 report, "How CBO Analyzes the Effects of Changes in Fiscal Policies on the Economy"; that report referred to a set of other reports describing spe- cific aspects of the agency's methods (CBO 2001, 201 2d, 2012f, 2012g, 2012h, 2013e, and 2014b). JCT (2003b, 2005, 2006, 2011a, 2011b, and

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98 Brookings Papers on Economic Activity ; Fall 201 5

2015a) has summarized its methodology as well. In addition, in each report

that presents such a macroeconomic analysis, CBO and JCT explain the key factors affecting the estimates.5

The approaches used by the two agencies differ in various specifics but

are quite similar in their overall structure. For estimating the short-term effects of changes in fiscal policies, the agencies focus on effects on the demand for goods and services (and also include effects from changes in labor supply). Reductions in taxes and increases in federal spending boost demand directly, while the opposite changes diminish it; those direct effects

propagate through the economy to an extent that depends on the response of monetary policy and other factors.6 Changes in demand are estimated to

lead to changes in output relative to potential output.

For estimating the longer-term effects of changes in fiscal policies, the

agencies examine effects on potential output. Both agencies use a Solow- type growth model and a life cycle (overlapping generations) growth model.7

In its Solow-type model, CBO focuses on the effects of changes in federal borrowing, marginal and average tax rates (through income and substitution effects), transfer payments (through income effects and, in some cases, sub-

stitution effects), and federal investment in physical infrastructure, educa- tion and training, and research and development. For example, an increase

in the marginal tax rate on labor income is estimated to reduce the supply of

labor, which in turn reduces capital accumulation. Similarly, JCT's Solow-

type model captures responses to changes in federal borrowing, marginal and average tax rates, and other factors. In their life cycle models, CBO and

5. There are recurring calls for CBO and JCT to be more transparent regarding many aspects of their analyses. However, achieving greater transparency would require the agen- cies to allocate more of their resources to explaining existing estimates rather than producing new ones, and Congress has been reluctant to accept that trade-off.

6. CBO projects actions by the Federal Reserve as part of its baseline economic projec- tions, and the agency has explained its method for estimating the Federal Reserve's reaction to changes in fiscal policies. For example, CBO (2015g) expects that the negative short-term effects of deficit reduction on output (stemming from a decrease in demand) will be "stronger when short-term interest rates are near zero . . . because under those conditions the Federal

Reserve is unlikely to adjust short-term interest rates to try to offset the effects of changes in federal spending and taxes" (p. 88).

7. JCT (201 la, 201 lb) also sometimes uses a growth model with infinitely lived agents. Separately, CBO (2014d, p. 12) discusses the possibility that changes in demand in the short term could affect potential output in the long term and concludes that the significance of the channels through which that might occur are "unclear," and thus "CBO does not cur- rently incorporate such channels in its analyses, although the agency continues to investigate the issue."

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DOUGLAS W. ELMENDORF 99

JCT include many of the same channels, although expectations also matter

explicitly - which presents a challenge for dynamic scoring that I return to below.

CBO generally reports both a central estimate and a range of estimates

for the macroeconomic effects of proposals. The range is based on the values for the key parameters found in the research literature; the range

for each variable "is intended to cover roughly the middle two-thirds of the likely values for the variable" (CBO 2015g, p. 73). The central esti- mate is intended to represent the middle of the distribution of possible outcomes (and can give weight to estimates from both the Solow-type model and the life cycle model).

To estimate the feedback from economic changes to the federal budget,

CBO accounts for the impact of changes in income on tax revenues and benefits (with the latter much less affected than the former), as well as other

factors. A one-dollar increase in overall output reduces the budget deficit

by roughly 20 to 25 cents, holding all else equal.8 The estimated budget- ary effects in a given year influence estimated economic developments in

subsequent years. A key challenge for CBO and JCT is assessing the changes that pro-

posals would generate to effective marginal tax rates on labor and capital,

the income of people with different propensities to consume, differences

in tax rates across types of capital, and changes in federal investment. CBO and JCT also modify their models as needed to capture the fea- tures of specific proposals. That process - as undertaken, for example, in the analyses of immigration reform and tax reform discussed below - sometimes requires a great deal of time and effort. In addition, the agen-

cies adjust parameter values over time in response to new evidence; for example, see CBO's (2012g) paper "A Review of Recent Research on Labor Supply Elasticities."

CBO's and JCT's analyses of the macroeconomic effects of proposals are

generally produced on much longer timetables than their budget estimates.

That difference arises both because estimating macroeconomic effects can

take considerable time and because the estimated budgetary impact (exclud-

ing macroeconomic effects) is one of the inputs into estimating a proposal's macroeconomic effects.

8. CBO (2015a, p. 133) provides a rule of thumb for the budgetary impact of lower out- put growth.

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1 00 Brookings Papers on Economic Activity, Fall 201 5

II.B. Comprehensive Immigration Legislation

In 2013, the Senate passed a bill to substantially increase the number of

people who could enter the country legally and to create a process through

which many people who are currently present in the country on an illegal basis could gain legal status. CBO and JCT provided estimates for the leg-

islation in two separate documents released simultaneously: a cost estimate that included some but not all of the expected macroeconomic effects of the bill (CBO 2013b), and a supplemental analysis of the bill's total macro- economic effects and the incremental budgetary impact of the economic changes not included in the cost estimate (CBO 2013c). CBO (2013c, p. 2) explained the analysis this way:

[Since the legislation] would significantly increase the size of the U.S. labor force, assuming that total employment was unchanged would imply that any employment

of the additional immigrants would be offset one-for-one by lower employment elsewhere in the population. Because that outcome would be highly implausible, CBO and JCT relaxed the assumption of fixed GDP and employment and incor- porated into the cost estimate their projections of the legislation's direct effects on the U.S. population, employment, and taxable compensation. Nevertheless, to remain as consistent as possible with the estimating rules CBO and JCT fol- low for almost all other legislation, the cost estimate . . . does not incorporate the budgetary impact of every economic consequence of the bill. The [supplemental] analysis . . . includes some additional budgetary effects stemming from changes in the productivity of labor and capital, the income earned by capital, the rate of return on capital (and therefore the interest rates on government debt), and the differences in wages for workers with different skills.

That is, the cost estimate excluded macroeconomic changes that could be excluded without making the estimate nonsensical, and the supplemental analysis included all of the macroeconomic changes that CBO was able to estimate.

In the cost estimate, CBO and JCT estimated that the bill would reduce

cumulative budget deficits by about $200 billion during the first decade after

enactment and about $700 billion during the following decade. In the sup- plemental report, CBO estimated that the bill would raise output by roughly

3 percent by the end of the first decade; additionally, it estimated that eco- nomic effects not included in the cost estimate would have no further net

effect on the cumulative deficit in the first decade but would further reduce

the cumulative deficit in the second decade by about $300 billion.

II.C. Affordable Care Act

When CBO and JCT estimated the budgetary effects of the ACA and its precursors in 2009 and 2010, they incorporated the impact of many changes

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DOUGLAS W. ELMENDORF 101

in the behavior of individuals, employers, health insurers, and health care

providers. However, the agencies did not include the impact of certain other changes in behavior because of the long-standing convention for cost esti- mates that overall output would be unaffected.

By contrast, given the recent congressional push for dynamic scoring, CBO

and JCT's estimate in mid-2015 of the effects of repealing the ACA included

macroeconomic changes. The estimate incorporated, among other factors: short-term effects on aggregate demand of changes in federal spending and

taxes; effects on labor supply of changes in tax rates for certain higher-income

people and of changes in subsidies for health insurance for certain lower-

income people; and effects on capital investment of changes in tax rates, labor supply, and federal borrowing. The largest macroeconomic impact of

repealing the ACA was estimated to stem from repealing the subsidies for health insurance.9 The agencies concluded:

Repealing the ACA would increase federal budget deficits by $137 billion over the 2016-2025 period . . . , [which incorporates] the net effects of two com- ponents: Excluding the effects of macroeconomic feedback . . . , federal defi- cits would increase by $353 billion over the 2016-2025 period if the ACA was repealed. Repeal of the ACA would raise economic output, mainly by boosting the supply of labor; the resulting increase in GDP is projected to average about 0.7 percent over the 2021-2025 period. Alone, those effects would reduce federal deficits by $216 billion over the 2016-2025 period. (CBO 2015h, p. 1)

I I.D. Congressman Camp's Tax Reform Proposal

In early 2014, Congressman Dave Camp, then the chair of the Ways and

Means Committee, put forward a comprehensive proposal for broadening the bases of the individual and corporate income taxes, adjusting tax rates,

9. The estimate of the effects on labor supply drew heavily on CBO's published analy- sis during the preceding several years. CBO (2009c) examined various channels through which changes to the health insurance system could affect labor markets; however, specific proposals were still in formative stages at the time, so the report did not provide quantita- tive estimates. In late 2009 and early 2010, congressional interest in the evolving health care legislation focused on its effects on the federal budget, health insurance coverage, insur- ance premiums, and existing federal programs, so CBO and JCT's analysis focused on those issues. After the ACA was enacted, CBO needed to incorporate the law's economic effects into the baseline economic projections. As part of that process, CBO (2010b, pp. 48-49) reported that it expected the ACA to reduce aggregate labor supply by an amount that would reduce labor compensation by roughly one-half percent after it was fully phased in. A few years later, during a careful review of its labor-market projections, CBO (2014a) updated that estimate to roughly one percent, with the revision arising because the agency "incorpo- rated into its analysis additional channels through which the ACA will affect labor supply, reviewed new research about those effects, and revised upward its estimates of the respon- siveness of labor supply to changes in tax rates" (p. 118).

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1 02 Brookings Papers on Economic Activity , Fall 201 5

and making other changes to those tax systems. JCT published a set of reports

analyzing that proposal, including estimates of the proposal's distributional

consequences, revenue effects (excluding any impact on the overall economy),

and overall economic impact. Based on the convention of fixed output, JCT (2014b) estimated that the proposal would be effectively revenue-neutral,

raising federal revenues by $3 billion over the next decade. In its macro- economic analysis, JCT (2014c, p. 21) wrote:

Broadening of the individual and corporate income tax bases through elimina- tion of many preferences in the form of deductions, exemptions, and tax credits allows for a reduction in average and effective marginal tax rates for most indi- vidual taxpayers, which provides both an incentive for increased labor effort, and an increase in demand for goods and services. These changes also reduce the after-tax return to investment under many modeling assumptions, providing an incentive for a reduction in the U.S. domestic capital stock. On net, these changes are expected to result in an increase in economic output relative to present law.

JCT estimated that the proposal would raise the level of output by between

0.1 percent and 1.6 percent, on average, during the 2014-23 period. That additional output was estimated to reduce cumulative deficits by between

$50 billion and $700 billion during the 2014-23 period.

II.E. Other Illustrative Analyses

In the past several years, CBO and JCT have provided estimates of the budgetary feedback from the macroeconomic effects of other proposals as well.

Each year, the agencies publish detailed estimates of the president's bud-

get proposals based on the conventional assumption that the overall economy

would be unaffected, and CBO separately (and somewhat later) publishes an analysis of the economic effects of the proposals and the feedback to the federal budget. As an example, CBO (2012b, 2012c) estimated that, excluding macroeconomic effects, the cumulative deficits under the pres- ident's proposals would be $3.2 trillion during the 2013-17 period and another $3.2 trillion during the 2018-20 period - and that including macro- economic effects, the cumulative deficits would be $3.0 trillion to $3.2 tril-

lion during the first half-decade and $3.3 trillion to $3.6 trillion during the second half-decade.

In addition, CBO's annual analysis of the long-term budget outlook includes estimates of economic and budgetary outcomes under alternative

policies, with the budgetary effects taking into account the economic effects

and vice versa (CBO 2015e). Moreover, in some years, CBO has published

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DOUGLAS W. ELMENDORF 103

estimates of the economic effects and budgetary feedback of deficit paths specified by the chair of the House or Senate Budget Committee (for exam-

ple, CBO 2015e). JCT has also released macroeconomic analyses of the Jobs and Growth Reconciliation Tax Act of 2003 (JCT 2003a), the American

Recovery and Reinvestment Tax Act of 2009 as reported by the Ways and

Means Committee (JCT 2009, pp. 234-39), and other proposals.

III. The Case for Including Macroeconomic Effects in Budget Estimates

A natural starting point for evaluating dynamic scoring is to consider the

objectives of the budget estimating process. After providing that context, I

explain why including macroeconomic effects in estimates for certain leg- islative proposals would both improve the accuracy of budget estimates for

those proposals and provide important information about their economic effects. However, attempting to include macroeconomic effects in all bud- get estimates would not be appropriate because of limited staffing and time, and because it would raise another set of issues that would have to be addressed as well.

1 1 I.A. What Should Be the Objectives

of the Budget Estimating Process?

In my judgment, CBO and JCT should provide estimates for legislative

proposals that measure the full budgetary effects as accurately as possible

and illuminate notable nonbudgetary effects , subject to several significant constraints.

To "measure the full budgetary effects as accurately as possible," esti- mates would ideally equal the expected present value of proposals' budget- ary effects over a long time horizon. A long horizon is appropriate, because the effects of proposals could last into the indefinite future, and CBO and JCT should analyze proposals as specified and not presume the enact- ment of any future legislation to modify or undo them. In particular, it is untenable for agencies working for Congress to make specific predictions about the future decisions of current members or of members who will be

elected over time.10 Present value is appropriate because future events are

10. However, some approaches to estimating the macroeconomic effects of legislation do require limited predictions about future policies; this issue is addressed in section IV.

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1 04 Brookings Papers on Economic Activity, Fall 201 5

discounted in other contexts. The expected outcome is appropriate because

it minimizes the mean squared error of estimates.11

To "illuminate notable nonbudgetary effects" - such as effects on the over-

all economy - estimates would ideally provide quantitative, or at least quali-

tative, information about such effects. That objective is appropriate because reliable and timely information about the nonbudgetary effects of proposals

is important for policymakers to receive and is not readily available from sources other than CBO and JCT. In particular, advocates and opponents of

proposals often generate overly optimistic or pessimistic estimates of their effects, while independent analysts often are not familiar with the details of

proposals and do not possess the models needed to estimate their effects, so they have difficulty producing reliable estimates quickly.

However, those ideal approaches cannot be fully put into practice, due to four significant constraints, as follows:

First, estimates should be easily understandable by members of Congress,

their staffs , and outside observers , and they should be resistant to misinter-

pretation. Many members, staff, and observers have little training in quan- titative analysis or budgeting, and most have limited time for reviewing budget estimates. Also, advocates and opponents of proposals often try to

cite estimates in ways that support their own positions, so it is important that

estimates be clear and difficult to use in misleading ways. Second , estimates should be based on methodologies that are applied

consistently across related proposals and are credible to members of Con-

gress, their staffs , and outside analysts. Using consistent methodologies is crucial to ensuring that proposals can be compared meaningfully. Using methodologies that are credible is crucial to maintaining Congress's confi- dence in the estimates, to ensuring that the estimates reflect the consensus of informed professional thinking, and to protecting CBO and JCT from political pressure. By contrast, using methodologies that seem arbitrary or

can be easily manipulated by lawmakers' construction of proposals in par- ticular ways undermines confidence in the agencies' estimates for those proposals and for other proposals as well.

Third, estimates should be produced quickly enough to serve the legisla- tive process and structured in ways that fit the process. Thus, estimates should

include the information sought by congressional leaders or committees as

1 1 . For certain financial activities of the government where risk is apparent and can be readily assessed, I think the estimated budgetary effect should not equal the expected present value of the activities but instead should incorporate an adjustment for the cost of the risk. That issue lies beyond the scope of this paper.

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DOUGLAS W. ELMENDORF 105

they develop proposals and by members of Congress as they vote on pro- posals. And when the legislative process moves swiftly, estimates should be prepared and updated rapidly as proposals are modified. Fourth , estimates need to be prepared using the resources available to

CBO and JCT. Although the number of congressional requests for esti- mates has increased considerably in recent years, the funding provided to the agencies has left their staffing little changed, on balance.

Many aspects of the budget estimating process represent compromises between those constraints and the idealized estimates described above. As

one important example, official budget estimates generally apply to the coming decade rather than a longer time period, because the estimating methodology needed for a longer period would require additional resources to develop, would usually be less credible, and would lead to estimates that

were more prone to misinterpretation. However, certain proposals would have longer-term effects that are quite different from their effects in the coming decade, and in those cases CBO and JCT try to provide some infor- mation on longer-term effects. The precision of that information and the

time period for which it is provided vary across proposals, depending on congressional interest, on the agencies' assessment of the resources required to generate the information, on the credibility of the methodology used, and

on the risk of leaving results open to misinterpretation. Thus, CBO has analyzed certain proposals to change Social Security over 75 years (CBO 2010a), but it generally does not analyze proposals to change federal health care programs beyond 25 years because of the especially large uncertainty involved in predicting the evolution of the health care delivery and financ- ing systems.

As another example, official budget estimates generally show nominal cash flows rather than inflation-adjusted or present- value cash flows because

nominal flows are more straightforward than the alternatives and because

the distortion relative to showing present values is fairly small over a decade.

The principal exception is estimates for federal credit programs, for which nominal cash flows over a decade are often a gross misrepresentation of the full budgetary effects over a long horizon; for these estimates, accrued costs are therefore used instead.

As a final example, official budget estimates sometimes exclude factors that might affect the budgetary impact of proposals but whose sign or mag-

nitude are especially uncertain. That exclusion may seem inconsistent with the objective of measuring budgetary impact as accurately as possible: The mean squared error of a budget estimate reflects the underlying uncertainty of all relevant factors, even if estimates of some of the factors are set to

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1 06 Brookings Papers on Economic Activity ; Fa 1 1 201 5

zero; therefore, if CBO or JCT can generate informed estimates of those factors, including them in the overall budget estimate would probably increase the accuracy of the estimate. However, that point cannot be proven

as a general rule. Although in-sample prediction errors from linear regres-

sion models are minimized by including all relevant factors, including additional factors does not necessarily minimize out-of-sample prediction errors from nonlinear models (which is what CBO and JCT often use).12

Moreover, including factors that are especially uncertain can diminish the credibility of the estimating process because when the likelihood func-

tion for a factor is particularly flat, the agencies' choice of a specific value

often seems arbitrary. Therefore, for factors whose budgetary impacts are probably small and are especially uncertain, the probable improvement in

accuracy from including them in budget estimates may be outweighed by the risks of inadvertently diminishing accuracy and weakening the agen- cies' credibility. That condition is particularly likely to be satisfied when the

net budgetary impact of a set of excluded factors might be either positive or

negative.13

1 1 LB. Similarity between Macroeconomic

and Nonmacroeconomic Effects

Changes in federal tax and spending policies can affect people's behav- ior in many ways, and those behavioral responses can affect the federal budget. Some of those responses affect the composition of output or dis- tribution of income but not total output and income, while other responses affect total output and income as well as their composition and distribution.

A natural presumption is that measuring the full budgetary effects of legis-

lative proposals as accurately as possible requires including the impact of all of those behavioral responses.

For example, if marginal income tax rates were increased, a number of responses would ensue. The share of people's income devoted to activi- ties whose costs can be deducted from income, such as mortgage interest

12. See CBO (2015f, pp. 21-22) for a related discussion. 13. For example, CBO (2014a, p. 123) discussed some ways in which the ACA might

affect productivity and concluded: "Whether any of those changes would have a noticeable influence on overall economic productivity, however, is not clear. Moreover, those changes are difficult to quantify and they influence labor productivity in opposing directions. As a result, their effects are not incorporated into CBO's estimates of the effects of the ACA on the labor market."

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DOUGLAS W. ELMENDORF 107

payments and charitable contributions, would increase. The share of com-

pensation received in nontaxable forms, such as employers' contributions to pensions and health insurance, would increase. The amount of labor supplied would decrease (if the substitution effect outweighed the income

effect), and the amount of saving would decrease (again, if the substitu- tion effect outweighed the income effect). The first two responses are typically included in conventional estimates, and the latter two are not. However, when the responses are described in this manner, there is no clear conceptual reason to treat the latter two responses differently from the first two.

Of course, one difference between those two sets of responses is that reductions in labor supply and saving would affect total output whereas shifts in the uses of income and types of compensation would not. Thus, the reductions in labor supply and saving can be labeled macroeconomic effects, while the other shifts are purely microeconomic. Still, because all

of the responses stem from actions by people and firms, there is no clear rationale for including some in budget estimates and excluding others.

The reductions in labor supply and saving that are spurred directly by the increase in marginal tax rates could generate further economic changes, such as shifts in pretax wages and in the pretax return to capital, which would have further effects on labor supply and saving. One might argue that

those additional effects should be excluded from budget estimates because

of their indirectness. However, indirect effects can be quantitatively impor-

tant. Consider an example from a legislative proposal that did not change tax rates: The immigration legislation approved by the Senate in 2013 would have significantly increased the supply of labor, which would have induced additional capital investment. Ignoring the increase in labor supply would have substantially understated the impact of the legislation on output;

including that increase in labor supply without including the induced growth

of the capital stock would still have understated the impact of the legislation

on output and would also have overstated its impact on wages. Changes in federal policies can affect total output and income in many

other ways as well. Changes in tax rules can affect investment in human capital and the allocation of physical capital, changes in federal benefits can affect labor supply and saving, and changes in federal spending for infrastructure, education and training, and research and development can affect labor supply, saving, and productivity. As with the effects of changes

in marginal tax rates, there is no clear conceptual basis for including in budget estimates the effects of such policy changes on specific parts of the economy but not the effects on aggregate economic variables.

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1 08 Brookings Papers on Economic Activity ; Fa II 201 5

1 1 1.C. Advantages of Including Macroeconomic Effects

in Certain Budget Estimates

Based on CBO's and JCT's past analysis of the macroeconomic effects of legislative proposals and their budgetary feedback, I conclude that using dynamic scoring in budget estimates for certain proposals would improve the accuracy of those estimates , provide important information about the

economic effects of those proposals , and (under certain conditions) satisfy the significant practical constraints for budget estimates listed earlier.

Some proposals' estimated macroeconomic effects would have signifi- cant budgetary consequences. For example, the estimated macroeconomic effects of the Senate's 2013 immigration bill, the ACA, and Congress- man Camp's tax plan (based on the midpoint of the reported estimates) all have budgetary impacts equal to hundreds of billions of dollars over a decade. Moreover, if dynamic scoring had been applied to the economic stimulus legislation of 2009 (the American Recovery and Reinvestment Act), its estimated budgetary effect would have been reduced by hundreds

of billions of dollars: CBO (2009b) estimated that the legislation would raise output by more than $800 billion over the following decade, and that

additional income would have been estimated to reduce budget deficits by about $200 billion compared with an estimated budgetary cost of the bill of roughly $800 billion (CBO 2009a).14

To be sure, accounting for the estimated macroeconomic effects of those

proposals would have improved the accuracy of the official budget esti- mates only if the estimates of the macroeconomic effects had been some-

what accurate.15 Unfortunately, assessing the accuracy of CBO's and JCT's estimates is quite difficult. Many proposals that the agencies examined were

not enacted, and the proposals that were enacted were just a few of many fac-

tors affecting the economy and the budget, so isolating their impact is hard

even in retrospect (CBO 2013a, 2015b). In my judgment, however, both agencies' methodology for conducting macroeconomic analysis reflects the consensus of informed professional thinking, and that consensus provides a useful, albeit imperfect, basis for predicting the macroeconomic effects of legislative proposals. Moreover, there is no reason to believe that their

14. The central estimate in JCT (2009) was that the tax provisions in the bill (as approved by the Ways and Means Committee) would increase output by about one-half percent in the short run, leading to a reduction in the cost of those provisions of about one-seventh of the conventional estimate.

15. The further step of estimating the budgetary feedback from estimated macro- economic effects is fairly straightforward and can be done reasonably accurately.

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DOUGLAS W. ELMENDORF 109

estimates of macroeconomic effects are generally less accurate than their

estimates of other effects of complex proposals, although certainly the agencies should continue to strive to improve their analyses.

The effects of some legislative proposals on the overall economy are very

important for policymakers to understand. For example, while the macro- economic effects of immigration reform and tax reform are among the most

touted reasons for pursuing those policy changes, different approaches to immigration reform - such as increasing the numbers of high-skilled and low-skilled immigrants by different amounts - could lead to very differ-

ent macroeconomic effects.16 Similarly, different approaches to tax reform,

such as using revenues raised by broadening tax bases to reduce marginal tax rates or to make targeted inframarginal tax reductions, could lead to very different macroeconomic effects.

As another example, major changes to benefits for lower-income people

could have notable effects on the economy by altering labor supply, and those effects could be an important criterion in evaluating such changes. To

use Arthur Okun's famous metaphor, we should understand the leakiness of different buckets for transferring resources to lower-income people. And

as a further example, policy changes that reduced federal deficits to differ- ent degrees and at different speeds would generally have different macro- economic effects in the next few years and in the longer run.

Estimates of macroeconomic effects can be valuable even when those

effects appear small to some observers. For example, CBO (2015e) found that this year's budget resolution - which calls for a reduction in cumula-

tive deficits over the next decade of about $5 trillion excluding interest savings and macroeconomic effects - would raise the level of real output in 2025 by 'Vi percent, which amounts to an increase in the average annual

growth rate over the coming decade of 0.15 percentage point. If that effect is surprisingly small to some people, the value of the estimate is increased, not diminished.

In addition, objective and timely information about the macroeconomic effects of legislative proposals is not readily available from sources other than CBO and JCT. Advocates and opponents of particular policies usually find ways to have their perspectives well represented in the congressio- nal and public debates. However, independent, reliable analysts generally

16. Changes in overall output do not necessarily correspond to changes in economic well-being and should not be interpreted as such. For example, CBO (2013c) distinguished carefully between the effects of the-Senate's 2013 immigration legislation on total output and on output per resident.

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110 Brookings Papers on Economic Aďivity, Fall 201 5

have more difficulty than the agencies do in completing their analyses on a

timely basis (because doing careful analysis is hard and because those ana-

lysts often are not close to the policy development process) and having their

analyses heard. Including macroeconomic effects in budget estimates would ensure that CBO and JCT devote resources to analyzing those effects in a timely way. Also, because of the attention paid to official budget estimates

in the legislative process, including macroeconomic effects in those esti- mates would ensure that the effects received attention.

The usefulness of such attention depends in part on the clarity of CBO's

and JCT's descriptions of estimated macroeconomic effects. Describing such effects can be challenging, but the agencies now have considerable practice doing so in their supplementary analyses and are quite able to do so in official budget estimates as well. For example, in the agencies' report on

repealing the ACA, the logic and magnitude of the macroeconomic effects are laid out clearly and in a manner that nicely parallels the discussion of the

repeal's nonmacroeconomic effects. Lastly, under certain conditions CBO's and JCT's estimates of the macro-

economic effects of legislative proposals can satisfy the key constraints described earlier: being understandable and resistant to misinterpretation,

based on a consistent and credible methodology, produced quickly enough

to serve the legislative process, and prepared using the resources available to the agencies. Those issues are addressed in the remainder of the paper.

III.D. Limiting Macroeconomic Effects to Budget Estimates for Major Proposals

Despite the advantages of including macroeconomic effects in budget estimates for legislative proposals, I conclude that such effects should be incorporated only in estimates for major proposals. Specifically, apart from proposals for which dynamic scoring is requested by the chair or ranking member of the House or Senate Budget Committee, I think that dynamic scoring should be applied only to proposals whose estimated nonmacro- economic effects on revenues, spending, or deficits, relative to the baseline, exceed a given threshold.

CONSIDERATIONS IN SUPPORT OF LIMITED DYNAMIC SCORING That recom-

mendation is based on three considerations (although there are legitimate counterarguments that are discussed below). First, CBO and JCT have the resources to conduct careful macroeconomic analyses for only a limited number of legislative proposals each year. All of the estimates of macro- economic effects described above involved significant conceptual and practical challenges and required a great deal of analysts' time to complete.

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DOUGLAS W. ELMENDORF 111

The agencies can devote that much time to only a very small share of the

thousands of proposals they examine each year.

Second, applying rules of thumb to produce estimates of the macro- economic effects of other proposals would generally violate the important constraint that estimates be based on methodologies that are credible and cannot be easily manipulated. The macroeconomic effects of proposals can

be complex and can vary considerably with the specifics of the proposed pol-

icy changes, the state of the economy, and the time horizon being examined.

For example, when CBO (2015c) examined three ways of reducing spend- ing for the Supplemental Nutrition Assistance Program (commonly known as "food stamps"), the agency found that even the sign of some policies' net effect on labor supply was unclear without detailed analysis. Similarly,

when JCT (2005) examined three approaches to reducing taxes by $500 bil-

lion, it found that their effects on the economy differed greatly.

In addition, the agencies' estimates of short-term macroeconomic effects

depend importantly on the posture of monetary policy. Rules of thumb would not capture those kinds of crucial nuances. Moreover, developers of proposals might exploit rules of thumb by structuring their proposals or labeling aspects of their proposals in ways that would generate more favor-

able estimated macroeconomic effects and thus lower estimated budgetary

costs. CBO and JCT currently minimize such gaming by basing their non- macroeconomic estimates on a careful understanding of the substance of proposals rather than the application of arbitrary rules. Even if using rules of thumb to estimate macroeconomic effects could improve the accuracy of budget estimates on average, doing so would endanger the credibility of the estimating process.

Third, the proposals for which CBO's and JCT's estimates of macro- economic effects would generally be most valuable are the ones with the largest estimated budgetary impacts apart from such effects - because those proposals are likely to produce significant macroeconomic effects. To

be sure, some proposals that would not cause large changes in revenues or spending would also produce significant macroeconomic effects, but iden- tifying them with a mechanical algorithm would be difficult. For example, Congressman Camp's comprehensive tax plan had a very small estimated effect on revenues apart from macroeconomic effects - because the large estimated effects of some individual provisions of the plan were largely offsetting - but significant estimated macroeconomic effects. A threshold for dynamic scoring based on the gross budgetary effects of a proposal's individual provisions would have identified his plan. However, a criterion based on so-called gross effects would not be very robust, because the

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112 Brookings Papers on Economic Activity , Fall 201 5

method of constructing an estimate and the level of detail shown in a table

describing the estimate can alter the magnitude of the reported increases and decreases.17

Thus, the best way to choose which proposals with small estimated bud- getary impacts relative to the baseline should be scored dynamically is to allow for requests from key congressional leaders. In principle, at least, the budget committees are responsible for the budget process, and the official

budget estimates are designed to support that process, so it makes sense to

allow for requests from those committees. One might also allow for requests

from the House Ways and Means Committee, the Senate Finance Commit-

tee, and the House and Senate Appropriations Committees, which are the other principal consumers of CBO's and JCT's estimates. However, if all of

those committees could request dynamic estimates, the number of requests might become unmanageably large, so I slightly prefer to vest the authority

only in the budget committees. What is more important is to ensure that

such requests are not skewed in the direction of any one party's political interests. Therefore, the ranking members as well as the chairs of the com-

mittees should be allowed to make requests. By contrast, the new House rule and this year's budget resolution grant that power only to the budget committee chairs.

In my view, a sensible threshold for automatically including macro- economic effects in budget estimates would be estimated changes in reve- nues, spending, or deficits (excluding any macroeconomic impact) relative

to the baseline exceeding one-quarter of one percent of projected output over the 10-year budget window. That threshold equals about $575 billion currently (based on CBO [2015a]) and probably would lead to dynamic scoring for only a few proposals each year, which would be a manageable increase in CBO's and JCT's workloads. Neither the Senate's 2013 immi-

gration proposal nor Congressman Camp's tax plan would have met that threshold, though clearly at least one leader of a budget committee would have requested dynamic scoring for each.

The new House rule and this year's budget resolution use a quarter-point threshold but apply it to any single year in the budget window rather than

17. For example, the ACA included significant changes to the drug benefit in Medicare, some of which increased federal spending and others of which reduced it. One might view the estimated net effect on spending of those changes to be the combination of a gross esti- mated increase and a gross estimated decrease. However, the changes interacted with each other in significant ways, so CBO estimated their effects as a package and never identified elements of the estimate separately.

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DOUGLAS W. ELMENDORF 113

the 10-year period as a whole. That approach generates thresholds of about

$45 billion in 2015 and about $70 billion in 2025 based on projected output,

and naturally it will cause more bills to be scored dynamically than my pre-

ferred approach would. In particular, short-term extensions of expiring tax or spending provisions are more likely to receive dynamic scores, as in JCT (2015b). However, the estimated macroeconomic effects of such exten- sions are not always illuminating: Many people expect such provisions to be extended, even retroactively, but the baseline reflects the expiration of the provisions and therefore the assumption that people will gradually rec-

ognize that extensions are not occurring; as a result, the macroeconomic effects of extending the provisions are primarily the effects of people not

being surprised. Such effects can be complicated to estimate and difficult to

explain. In addition, extensions of that sort are often negotiated and voted on under tight timetables, which further complicates doing macroeconomic analysis.

TWO COUNTERARGUMENTS There are two noteworthy counterarguments to

limiting dynamic scoring to major proposals. One is that even if the macro-

economic effects of a proposal with limited budgetary impact are small relative to the overall economy, their feedback effect on the federal budget

could still be large relative to the nonmacroeconomic budgetary impact of the proposal. In those circumstances, careful dynamic scoring would significantly improve the accuracy of the budget estimate. However, CBO and JCT cannot do careful analyses of the macroeconomic effects of all proposals, and, as described above, using rules of thumb in place of care- ful analyses could reduce the accuracy of those estimates and diminish the

credibility of CBO's and JCT's estimates more generally. In my judgment,

those costs outweigh the benefits. The other counterargument is that focusing dynamic scoring on major

proposals would create an incentive for certain proposals to be bundled together or separated into pieces in order to lower their estimated budget- ary cost. However, sufficiently few proposals have budgetary impacts close to a quarter of a percent of output that this distortion would probably not be significant in practice. Moreover, allowing key congressional leaders to request dynamic scoring for less-significant proposals should ameliorate this problem.

Given the inability of CBO and JCT to apply dynamic scoring to all pro- posals, one might wonder whether avoiding dynamic scoring altogether is the best feasible approach because it would make the estimating methodol- ogy more consistent across proposals. However, policymakers do not usu- ally compare major proposals to less-significant proposals; major proposals

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114 Brookings Papers on Economic Activity ; Fall 201 5

are usually compared to other major proposals addressing similar issues, or else they are compared to the status quo, and both types of comparisons would be improved by dynamic scoring. In addition, as just noted, key congressional leaders could request dynamic scoring for less-significant proposals whose comparison to major proposals they considered especially valuable.

III.E. Other Important Issues

Five other issues concerning the inclusion of macroeconomic effects in

budget estimates deserve comment.

TIME HORIZONS First, estimates of macroeconomic effects of proposals should include both short-term effects stemming from shifts in aggregate demand and longer-term effects stemming from shifts in potential output.

Longer-term economic effects may be better guides to proposals' effects beyond the 10-year budget window, and since that window is a compromise

between the ideal of an even longer horizon and the practical advantages of a shorter horizon, a focus on longer-term effects may seem preferable.

However, the severe recession and slow recovery of the past several years

are a stark reminder that shortfalls in the demand for goods and services can

have large and persistent effects on the economy and the federal budget, so the effects of policy changes on aggregate demand can be quite impor- tant. Increasing aggregate demand was the principal objective of some proposals considered by Congress in the past several years, such as the economic stimulus legislation of 2009.

In addition, policy changes are sometimes reversed or modified in sub-

sequent years, so the short-term effects of changes are the effects most likely to occur, and policymakers may therefore give estimates of those effects greater weight in their decisions. Further, different policy changes that Congress sometimes compares - such as different time paths for reduc-

ing budget deficits by a given amount - would have different effects on aggregate demand, and illuminating those differences would be an impor- tant benefit of dynamic scoring.

RESOURCE constraints Second, when CBO and JCT conclude that they do not have the tools or time needed to do a careful analysis of a proposal's macroeconomic effects, they should state as much and not include such effects in the official budget estimate. Estimating macroeconomic effects carefully often requires a great deal of analysis, and legislation is some- times developed and amended quickly. Doing dynamic scoring without sufficient tools and time would endanger the credibility of the estimating process, as discussed above. That situation is especially likely to arise for

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DOUGLAS W. ELMENDORF 115

changes in regulatory policy that have small effects on the federal budget

apart from any macroeconomic effects. For example, substantial changes in federal regulation of the financial system or the environment could have

significant macroeconomic effects that would be important for policy- makers to understand and that could feed back to the federal budget in notable ways. However, CBO does not have much expertise in estimat- ing the macroeconomic effects of such regulatory changes, and acquiring enough expertise to do so quickly during the legislative process would require a significant increase in CBO's resources and would distract the agency from its core responsibility of informing budget policy. SHARED RESPONSIBILITY Third, CBO and JCT should share responsi-

bility for estimating the macroeconomic effects of proposals along the lines of their sharing responsibility for estimating the budgetary impact

of proposals excluding macroeconomic effects. Specifically, JCT should produce estimates of the macroeconomic effects of major proposals to change the federal tax code, CBO should do the same for major proposals to change federal spending, and the two agencies should collaborate in esti-

mating the macroeconomic effects of major proposals that would change both tax and spending policies (as they did in their estimate for repealing the ACA, released in June 2015 [CBO 2015h]). One challenge is ensuring that proposals that are similar in their substance receive similar estimates of their macroeconomic effects regardless of whether they are structured

as changes in tax policy or spending policy. For example, similar subsidies for similar activities should be estimated to have similar macroeconomic

effects, whether those subsidies take the form of tax credits or explicit fed-

eral spending. But that same challenge arises currently in estimating the budgetary impact of policies excluding their macroeconomic effects, and the challenge is met by ongoing interaction and coordination between CBO and JCT.

CONGRESSIONAL PROCEDURES Fourth, some congressional procedures may

need to be modified to accommodate dynamic scoring. For example, dynamic scoring may generate jurisdictional conflicts between some congressional committees. Because changes in spending that affected total output and income would affect revenues, the House and the Senate would need to

develop procedures for assigning budget targets to committees that allowed for such interactions. That problem would be somewhat ameliorated by the limited number of bills that would be scored dynamically. Other congres-

sional procedures would adapt naturally to dynamic scoring. For example, official budget estimates are used to assess the applicability of certain par-

liamentary "points of order"; if a proposal were scored dynamically, the

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116 Brookings Papers on Economic Activity , Fall 201 5

estimated budgetary feedback from the macroeconomic effects of the pro- posal would be incorporated in that assessment.

SUPPLEMENTARY REPORTS Fifth, there are some advantages to taking an alternative approach, in which CBO's and JCT's estimates of macro- economic effects and their budgetary feedback would be provided in sup- plementary reports rather than being included in official budget estimates,

although I think those advantages are outweighed by the approach's dis- advantages. The advantages of that alternative approach include the fol- lowing: It would avoid delaying the publication of budget estimates until macroeconomic analyses could be completed, which might be a consider- able period of time in some cases. It would maintain a consistent basis of fixed output for all official budget estimates, which might make it easier for

CBO and JCT to exclude macroeconomic effects when they did not have a solid analytic basis for assessing them. And it would avoid the jurisdic- tional problems that can arise between committees just discussed.

One might view as a further advantage of the alternative approach that

estimated macroeconomic effects and their budgetary feedback could be reported as ranges of possible outcomes rather than as the point estimates that the congressional budget process requires. This would also demonstrate the uncertainty of such macroeconomic analyses. Indeed, CBO and JCT should quantify that uncertainty by reporting ranges of estimates whenever

feasible, as I discuss in greater detail later. However, CBO (2014f, p. 12) explains that "providing ranges sometimes muddies, rather than enhances,

general understanding of our analysis because people tend to cite the part of a range they prefer," so CBO already tries to clarify the agency's findings by

reporting point estimates as well as ranges in the agency's macroeconomic analyses. Using those point estimates in official budget estimates would not distort the analyses or their presentation.

One might view as a different advantage of the alternative approach that it would enable the House and Senate to disagree about whether to include macroeconomic effects in official estimates and would enable members

of Congress, their staffs, and outside observers to evaluate the estimated

macroeconomic effects separately from the other estimated effects. How- ever, this would already be the case without the alternative approach. CBO (2015d, p. 23) has explained that "cost estimates [with dynamic scoring] will include all of the information that typically would be included if macro-

economic effects were not incorporated in the analysis, as well as addi- tional information related to the macroeconomic effects." Accordingly, the recent estimates for repealing the ACA and extending certain expiring tax provisions reported three projections: the estimated budgetary impacts

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DOUGLAS W. ELMENDORF 117

excluding macroeconomic effects, the estimated budgetary impacts of macro-

economic effects alone, and the estimated total budgetary impacts includ- ing macroeconomic effects. Including estimated macroeconomic effects in

official budget estimates in this manner does not preclude Congress and others from evaluating and using that information as they see fit.

Yet another seeming advantage of the alternative approach might be to

facilitate a procedural transition between the historical exclusion of macro- economic effects and their possible future inclusion. Such a transition would give CBO and JCT an opportunity to experiment with different methods of analysis and presentation, and it would give Congress and others an opportunity to learn about the agencies' macroeconomic analy- sis and develop procedures for using that information. In fact, however, that transition has effectively been under way for some time. As discussed above, both CBO and JCT have published many analyses of the macro- economic effects of legislative proposals as well as reports on their meth- odology for such analyses. Moreover, the recently published estimates for repealing the ACA and extending expiring tax provisions did not reveal any problems that would suggest dynamic scoring is "not ready for

prime time."

In addition, the alternative approach would have some significant dis- advantages. Leaving macroeconomic effects out of budget estimates would reduce the attention those effects receive, even though the effects can be

important for policymakers to understand. Also, separating the two types of budgetary effects of legislative proposals would make CBO's and JCT's estimates more difficult to understand for members of Congress, their staffs, and outside observers.

In my judgment, all those disadvantages of the alternative approach outweigh its limited advantages.

IV. Concerns about Including Macroeconomic Effects in Budget Estimates

A number of observers have expressed the view that including the macro- economic effects of legislative proposals in official budget estimates would worsen rather than improve the information those estimates provide. In this section I examine six important concerns noted by those observers that were not addressed, or were addressed only briefly, in the preceding section. In my view, the first two of these concerns apply with roughly equal force to macroeconomic and nonmacroeconomic effects of propos- als and thus are not compelling reasons for treating the former differently,

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118 Brookings Papers on Economic Activity ; Fa 1 1 201 5

the next three concerns represent true challenges in estimating macro- economic effects but can be addressed adequately by CBO and JCT, and the final concern is premised on an incorrect view of the agencies' role in the budget process.

IVA. Potential Political Pressure on CBO and JCT

One concern is that including macroeconomic effects of proposals in official budget estimates would increase political pressure on CBO and JCT to adopt modeling approaches or elasticities of behavioral responses that would overstate the positive effects of certain types of policies. I wel- come vigilance to guard against the risk that the agencies will be subjected to political pressure to modify their analysis in any regard. However, politi- cal pressure has not altered CBO's or JCT's estimates for legislation in past decades, and I doubt that dynamic scoring would substantially increase such pressure.

In my six years as CBO director, members of Congress, their staffs, and other observers were not hesitant to speak up when they disagreed with an estimate from CBO. That is not surprising, nor is it objectionable,

because CBO's and JCT's estimates are not above reproach. The appropri- ate response by the agencies to such criticism is to collect any information

that can be provided by those who disagree with the estimate, reconsider whether the agencies' analysis was correct, and revise the estimate if, and only if, the reconsideration shows that a different figure would be more

accurate. That process occurred a number of times while I was at CBO. However, at no point in those six years did anyone in a position of author- ity in Congress attempt to dictate a change in a CBO estimate or in a CBO

modeling assumption. Congressional leaders appear to understand the long- term value of maintaining CBO's and JCT's analytic independence.

Similar disagreements with CBO's and JCT's macroeconomic analyses have occurred in the past and would occur in the future if dynamic scor- ing were adopted. However, the risk of political pressure does not seem greater for estimates of macroeconomic effects than for estimates of non- macroeconomic effects. On the one hand, there may be more observers who

have strongly held views about key parameters underlying macroeconomic estimates - such as the elasticity of labor supply - than have strongly held views about the less well-known parameters underlying nonmacroeconomic estimates. On the other hand, because macroeconomic estimates depend heavily on a small number of parameters and other modeling choices, CBO and JCT have publicly documented those choices more thoroughly than they have publicly documented the analytic underpinnings of some

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DOUGLAS W. ELMENDORF 119

nonmacroeconomic estimates. It is important, then, that CBO and JCT report publicly on any changes in their macroeconomic modeling (as CBO did during the past few years when it updated a number of aspects of that modeling).

IV.B. Uncertainty of Macroeconomic Effects

Another concern is that the macroeconomic effects of proposals are so

uncertain that including them in official budget estimates would degrade the

quality of the estimates. However, as noted above, the accuracy of the bud-

get estimates would probably be improved by including all of the factors for

which CBO or JCT can generate informed estimates, and macroeconomic effects meet that criterion when the agencies have the time and tools to do a

careful analysis. Moreover, many nonmacroeconomic effects of proposals are very uncertain as well, and in many cases there is less evidence to use

in quantifying those effects than in quantifying the macroeconomic effects of proposals.

As one important example, the extent of uncertainty regarding the macro-

economic effects of changes in tax rates can be gleaned from CBO's recent

review of evidence of the elasticity of labor supply. In a table summarizing estimates of the substitution elasticity for men and single women, CBO (2012g) showed values ranging from 0.04 to 0.84; in a corresponding table for married women, CBO showed values ranging from 0.03 to 0.70. Simi- lar uncertainty exists about other behavioral responses and other aspects of

CBO's and JCT's models of the macroeconomic effects of fiscal policies. However, uncertainty about those parameters is so apparent in part because they have been the subject of substantial research, which at least provides evidence for CBO and JCT to draw on.

For many of the behavioral responses underlying the nonmacroeconomic effects of fiscal policies, there is much less evidence for CBO and JCT to use, but that does not imply that uncertainty about the responses is smaller.

For example, the agencies' estimates of the nonmacroeconomic effects of the Senate's 2013 immigration legislation, the ACA, and Congressman Camp's tax reform plan all relied heavily on assessments of behavioral responses for which there is little evidence and experts are highly uncertain.

In addition, as noted above, the agencies' public documentation of their methodologies for estimating nonmacroeconomic effects is less expansive in some cases than their public documentation of their methodology for estimating macroeconomic effects. Thus, there is no good reason to view the agencies' estimates of macroeconomic effects as less credible than their estimates of nonmacroeconomic effects.

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1 20 Brookings Papers on Economic Activity ; Fall 201 5

Note also that excluding macroeconomic effects from budget estimates for

proposals that might have significant macroeconomic effects - and doing so only because of a historical convention that many consider arbitrary - itself

diminishes the credibility of budget estimates. In sum, I think that including

macroeconomic effects (under the conditions described in this paper) would enhance the credibility of the official budget estimates.

Although the budget process focuses on point estimates, quantifying the

uncertainty of estimated macroeconomic effects may be useful to mem- bers of Congress, their staffs, and outside analysts, and I think that CBO

and JCT should do that whenever feasible.18 For example, the range of estimates that JCT published for Congressman Camp's tax plan provided a measure of uncertainty, and, as noted above, CBO typically presents its estimates of macroeconomic effects with a range as well as a central estimate.

IV.C. Potential Bias toward Tax Cuts Relative to Spending Increases

A further concern is that applying dynamic scoring to proposals affect-

ing federal taxes but not proposals affecting federal spending would distort policymakers' decisions in favor of tax cuts relative to spending increases. For example, if lower tax rates raise output by increasing labor

supply, and greater infrastructure spending raises output by increasing the capital stock, then including the former effect in official budget esti- mates but excluding the latter effect would inappropriately encourage tax

rate cuts relative to infrastructure spending increases. That concern is, in

some ways, the opposite of a concern about the conventional approach to cost estimates, namely that excluding effects on labor supply tends to overstate the budgetary cost of tax cuts and understate the budgetary cost of benefit increases, thereby encouraging policymakers to increase taxes and benefits. In any event, the concern can be addressed by applying dynamic scoring to proposals that change spending as well as those that change revenues.

Indeed, as described earlier, CBO's analyses of macroeconomic effects include the effects of federal spending on the demand for goods and ser- vices, the effects of federal benefits on labor supply, and the effects on the

economy of federal investments in infrastructure, education and training,

18. Regarding uncertainty in CBO's estimates and the appropriate response by policy- makers, see Manski (2011), CBO (20140, and CBO (2015g, pp. 108-9).

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DOUGLAS W. ELMENDORF 121

and research and development.19 For example, CBO's annual economic analysis of the President's budget incorporates the effects of proposed changes in both spending and taxes. In addition, the estimated effects of the

ACA on labor supply stem partly from changes in the tax code and partly

from changes in spending for Medicaid (as well as some other aspects of the law), and those effects are treated in a completely parallel manner in the estimates.

Nonetheless, there are two obstacles to the goal of applying dynamic scor-

ing equally to federal spending changes and tax changes. One obstacle is that

the congressional budget process treats certain types of spending differently

from other types of spending and revenues. Roughly a third of noninterest

federal spending arises from annual appropriations by Congress (sometimes called "discretionary spending"), with the remaining roughly two-thirds reflecting payments for ongoing benefit programs (sometimes called "man-

datory spending"). Appropriations are currently split about equally between

defense and nondefense purposes, and about half of nondefense appro- priations go to investments in infrastructure, education and training, and research and development. The Congressional Budget Act of 1974 - which established CBO, the House and Senate Budget Committees, and many of the ground rules that govern the budget process - specified that CBO should not produce estimates for appropriations bills that are comparable to those it produces for other legislation, but instead should tally the amounts

specified in those bills and provide those tallies to the appropriations com-

mittees. Potential implications of appropriations for future tax revenues or benefit payments are not considered in that tallying process or in the subsequent legislative process. Perhaps because of that different proce- dural treatment, appropriations bills are excluded from the requirements for dynamic scoring in the new House rule and in the congressional budget resolution.

Moreover, if dynamic scoring were applied only to proposals with a sig-

nificant budgetary impact (excluding macroeconomic effects) relative to the

19. As CBO has noted, its analysis of those effects would benefit from further method- ological advances. CBO (2014d, p. 9) explained that the agency is "developing the capability to apply substitution elasticities as well [as income elasticities], but it does not currently have that capability for all transfer payments (although the agency has incorporated substitution elasticities in some specific analyses)." Similarly, the agency should enhance its capability to estimate the effects of federal investments in disaggregated categories and to estimate the long-term effects of federal benefits - although its analysis in those areas is limited mostly by a paucity of available research.

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1 22 Brookings Papers on Economic Activity ; Fall 201 5

baseline, as recommended above, few appropriations bills would meet that

criterion. The baseline for appropriations equals the previous year's appro- priations adjusted for inflation, or the statutory cap if one exists. Actual

appropriations in a single year rarely differ from the baseline by an amount

that exceeds a quarter of a percent of output over the coming decade, with the

most recent exception being the one-time burst of appropriations under the 2009 stimulus bill.

However, if the chairs and ranking members of the budget committees were allowed to request dynamic scoring for some bills with small esti- mated budgetary effects, also as recommended above, then they should be

allowed to make those requests for appropriations bills. It would be useful,

in my view, for CBO'to provide estimates of the macroeconomic effects and resulting budgetary feedback of consequential changes in appropria- tions.20 Unfortunately, the new House rule and congressional budget reso- lution explicitly exclude appropriations bills. I also think that CBO should publish a report with estimates of the macroeconomic effects of alternative

multiyear paths for federal investment and the budgetary feedback from those macroeconomic effects.

A second obstacle to applying dynamic scoring equally to spending changes and tax changes is that the macroeconomic effects of certain sorts

of federal spending are not fully felt within the 10-year budget window. Of

course, that same issue arises for certain sorts of federal tax changes. For

example, reductions in the marginal tax rate on capital income encourage additional private investment, and the resulting increase in the capital stock

(and thus output) occurs gradually. However, the problem may be especially acute for spending changes that involve investments. For example, most of the increment to output from a new bridge or improved highway (allow- ing for construction time and subsequent depreciation) occurs beyond the budget window. And most of the increment to output and income that may arise from improved health care, preschool education, or housing for low- income children occurs after those children have entered the labor force.

Therefore, the extent to which the budget window distorts the estimated macroeconomic effects of a change in spending (or tax) policy varies con- siderably depending on the characteristics of the policy change and the private or public investment that is increased or decreased.

This problem can be at least partly addressed by having CBO and JCT pro-

vide information about the effects of proposals beyond the 10-year budget

20. For a recent estimate of the macroeconomic effects of a change in appropriations - but not the budgetary feedback from those macroeconomic effects - see CBO (20151).

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DOUGLAS W. ELMENDORF 123

window. As noted above, when Congress is especially interested in a pro- posal's long-term effects or when CBO or JCT expect that a proposal's long-term effects would be very different from its effects within the budget

window, the agencies can provide that information. For example, CBO and JCT provided estimates for the second decade after enactment for the

Senate's 2013 immigration legislation and for repeal of the ACA, and in some cases CBO has estimated the effects of policy changes over even longer horizons (CBO 2010a, 2012e). In addition, the new House rule and congressional budget resolution explicitly require that qualitative infor- mation be provided about budgetary effects (including macroeconomic effects) beyond the 10-year budget window. Unfortunately, providing such information beyond the coming decade is challenging because, as noted earlier, the estimating methodology needed for a longer period would require additional resources to develop, would usually be less credible, and would lead to estimates that were more prone to misinterpretation in certain

ways. In particular, the evidence base that could be used to construct esti- mates of the long-term effects of benefit changes for low-income children remains limited.

Given the limitations on applying dynamic scoring to changes in fed- eral spending, one might wonder whether avoiding dynamic scoring for changes in federal taxes is the best feasible approach to official budget estimates because it increases the comparability of certain policies in a second-best way. Indeed, one might wonder whether dynamic scoring for

changes in taxes always provides useful information if some of the macro- economic effects of those changes occur beyond the 10-year budget win- dow. However, the macroeconomic effects of policy changes within the budget window can be important, even if later effects are somewhat dif- ferent. As noted above, the severe recession and slow recovery of the past

several years, and the fact that policy changes are sometimes reversed or modified over time, may make policymakers especially interested in short- term effects.21

In addition, the limitations discussed here do not create significant dis-

tortions in comparisons among many types of tax changes, comparisons between tax changes and the continuation of current tax law, compari- sons between tax changes and spending changes that do not have notable effects on investment, or comparisons between spending changes apart from investment and the continuation of current law. Even for comparisons

21. The particular problems that might arise in providing estimated macroeconomic effects for unsustainable policy changes are discussed in a later section.

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1 24 Brookings Papers on Economic Artivity, Fall 201 5

between tax changes and spending changes that affect investment, esti- mates for the decade-long budget window or estimates that extend into a second decade may still be more comparable if they include macro- economic effects. At the least, including such effects in budget estimates, even when imperfectly measured, would bring additional attention to those effects.

/V.Dģ Difficulty in Capturing Expectations of Future Fiscal Policy

Yet another concern is that accurately projecting the macroeconomic effects of proposals might require modeling expectations of future fiscal

policy, which would raise significant conceptual and practical difficulties. In particular, a reduction in current tax rates may have different effects on

labor supply and saving if people's expectations of future tax rates increase,

decrease, or remain the same - and modeling those expectations is challeng-

ing, especially if the proposal at hand represents an unsustainable change in policy. However, expectations of future fiscal policy are frequently left aside in other economic analyses, and CBO and JCT have developed meth- ods for handling this issue in their macroeconomic analyses.

Consider proposals that reduce marginal tax rates on labor income. When

CBO or JCT analyze such a proposal using their Solow-type growth mod- els, they apply labor supply elasticities drawn from the large empirical lit-

erature to the change in tax rates between the baseline and the proposal. Many papers in that literature do not explicitly measure expected tax rates but simply examine changes in labor supply that have resulted from given changes in contemporaneous tax rates. Therefore, the estimated elasticities

can be interpreted as the effect of a given change in current tax rates with

expected future tax rates adjusting in whatever way people expected them to

adjust, on average, in the past - which may appropriately reflect the fuzzi- ness of people's expectations about future tax rates. The Solow model does

not explicitly include expectations, so this sort of estimated elasticity fits logically, although it will generate a less accurate estimate in circumstances when anticipatory effects are important.

In contrast, people's behavior in life cycle growth models depends explic- itly on their expectations. If forward-looking people expected that federal debt would rise relative to output without limit, they would not hold federal

bonds, so the models can be used only to analyze sustainable changes in policies. Therefore, when CBO or JCT use their life cycle models to analyze a proposal that would increase deficits indefinitely, the agencies incorpo- rate future policy changes not specified in the proposal to offset the deficit increases. That situation is awkward, because a key principle of budget

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DOUGLAS W. ELMENDORF 125

estimates is that the agencies take proposals as written and do not predict

future legislation.

To minimize the influence of the assumed future policy changes on their

estimates, CBO and JCT generally report results for multiple alternative changes - for example, one estimate under the assumption that future reve-

nues are increased and another under the assumption that future spending is

reduced. In fact, the results often do not differ very much under alternative

assumptions (CBO 2015i). The agencies also defer the assumed changes as long as possible while still being able to solve the models (although con- gressional interest in receiving information about the effects of proposals beyond the 10-year budget window increases the difficulty of deferring the

assumed changes long enough that they would not affect the reported esti- mates). Even so, if a proposal would increase deficits indefinitely, which would have harmful economic effects, the inclusion in a budget estimate of additional policy changes not specified in the proposal might make the proposal look better than it really is.

Given those issues, I think that CBO and JCT should give less weight to estimates based on their life cycle models than to estimates using their

Solow-type models, except in circumstances where the anticipatory effects of proposals might be especially important.22 Indeed, the agencies have used their life cycle models less often than their Solow-type models in their macroeconomic analyses, perhaps because of the issue described here or else because the life cycle models can be more cumbersome in other respects.

It bears emphasis that the dependence of behavior on expectations of future fiscal policy also arises with estimates of certain nonmacroeconomic

effects of proposals, although it is rarely discussed in that context. For example, a reduction in current tax rates may have different effects on mort-

gage interest deductions or on employers' payments for health insurance,

depending on expectations of future tax rates. However, the empirical litera-

ture regarding such behavior does not explicitly measure expected tax rates, so CBO's and JCT's estimates can be interpreted as the effects of a given change in current tax rates with expected future tax rates adjusting in what-

ever way people had expected them to adjust, on average, in the past. That approach is somewhat unsatisfying, especially if the policy change at hand is not sustainable and therefore future changes will be needed, but there is no feasible alternative.

22. See CBO (2014c, pp. 14-15) for an example of how the agency combines results from its two models.

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1 26 Brookings Papers on Economic Activity ; Fall 201 5

IV.E. Potential Distortion to Estimates of Unsustainable Policy Changes Stemming From the 10-Year Budget Window

A further concern is that estimates of the macroeconomic effects of

unsustainable policy changes would be distorted by the 10-year budget window. For example, suppose that a reduction in tax rates was estimated

to raise output over the next decade but also to generate revenue losses that

were unsustainable (because the increase in output was not large enough for the tax reduction to pay for itself). If those same rates were later raised

to satisfy the government budget constraint, output would be estimated to

be lower in the long run. In that scenario, dynamic scoring over the budget window would credit the proposal with raising output even though the ultimate effect on output would be negative.

That scenario might occur, but it is not likely. First, a reduction in tax

rates without an offsetting broadening of the tax base or reduction in spend-

ing might well be estimated to lower output within the 10-year budget window, depending on the specifics of the tax reduction. For example, JCT

(2003a) estimated that the tax cuts enacted in 2003 would increase output during the first five years after enactment but decrease output later in the

decade, in part because the harmful effects of greater federal debt were esti-

mated to outweigh the favorable effects of lower tax rates. Similarly, CBO (2010c) estimated that extending the tax cuts originally enacted in 2001 and

2003 would raise output in the following few years but lower output later in the decade.23

Second, the harmful effects of greater federal debt increase over time

as debt compounds, while the favorable effects of lower tax rates gener- ally do not, so any tax-rate reductions that were estimated to raise output

throughout the first decade after enactment would be less likely to be esti- mated to do so in the second decade. Indeed, CBO (2010c) estimated that the negative effects on output of extending the tax cuts would be much larger after 30 years than after 10 years. Those long-term effects would be reported by CBO and JCT because, as noted above, the agencies try to provide information about long-term effects when they expect them to be very different from effects within the budget window. In addition, the

23. That result may seem surprising in light of CBO's (2005) estimate that a 10-percent reduction in federal tax rates on individual income would probably increase output in the second half of the decade after enactment. The difference between CBO's 2005 and 2010

estimates stems from several factors, including: the inclusion of inframarginal cuts in taxes under the 2001 and 2003 legislation; an increase in outstanding federal debt, which means that the rise in interest rates resulting from greater federal borrowing has a more significant effect on future deficits; and various improvements in CBO's modeling.

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DOUGLAS W. ELMENDORF 127

current rules regarding dynamic scoring require CBO and JCT to provide

information about the long-term effects of proposals.

Despite those points, suppose that a reduction in tax rates was, in fact,

estimated to raise output over the next few decades but also to generate revenue losses that were unsustainable. The unsustainable nature of the rate

reduction would be shown by the estimated effect of the proposal on fed- eral debt, so the need to make further policy changes to offset the budgetary

losses would be quite apparent. In addition, the increase in deficits might be

offset later not by reversing the tax-rate reduction but by making some other

policy change - and because that other change would have an effect on out- put that was not simply the opposite of the effect of the tax-rate reduction,

it is unclear whether the estimated effects of the rate reduction on output in

the first few decades would truly be misleading. Moreover, the estimated

macroeconomic effects of the rate reduction would not be the only aspect of the budget estimate that could be misleading; the estimated nonmacro- economic effects on the budget could be misleading as well, as would any distributional analysis or other analysis based on the rate reduction. In any event, it is not tenable for CBO and JCT to ignore the policy changes included in a legislative proposal even if those changes are not, by them- selves, sustainable.

IV J. Potential Benefits of Estimates that Err on the Side

of Overstating Budgetary Costs

One other concern about dynamic scoring arises from the view that policymakers tend to give insufficient weight to budgetary costs when developing and voting on legislative proposals, so CBO and JCT should provide budget estimates that tend to err in the direction of overstating those costs. As summarized (but not necessarily endorsed) by the Com- mittee for a Responsible Federal Budget (2012, p. 1), the argument is then

made that excluding the macroeconomic effects of proposals from official

budget estimates would make "dynamic gains a 'bonus' to help further reduce the deficit."

However, dynamic scoring does not consistently reduce the estimated budgetary cost of proposals relative to nondynamic scoring. As noted earlier,

CBO (2010c) estimated that extending the broad tax cuts originally enacted in 2001 and 2003 would reduce output by the latter part of the decade after enactment, so dynamic scoring would have shown a more negative impact on the budget than nondynamic scoring. Also, CBO (2014a) estimated that the expansion of federal subsidies for health insurance under the ACA was reducing labor supply and thereby federal revenues, so dynamic scoring of

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1 28 Brookings Papers on Economic Aďivity ; Fall 201 5

the ACA would have shown a more negative impact on the budget than nondynamic scoring.

More fundamentally, I do not think it is appropriate for CBO and JCT

to try to nudge policymakers toward smaller budget deficits by providing estimates that tend to overstate the budgetary costs of proposals. Instead,

the agencies should provide estimates that are in the middle of the distribu- tion of possible outcomes and leave policymakers to make decisions based on their own views of desirable outcomes and acceptable risks.

V. Conclusion

Including macroeconomic effects in budget estimates for major legislative

proposals - except when CBO and JCT do not have the tools or time to do a careful macroeconomic analysis - would improve the accuracy of those budget estimates and would provide important information about the eco- nomic effects of those proposals. Therefore, I conclude that dynamic scor-

ing should be used for major proposals when the agencies have the tools and time to do a careful macroeconomic analysis.

To complement that greater commitment to analyzing the macroeconomic

effects of legislative proposals, CBO and JCT should also make a greater commitment to analyzing proposals' distributional effects. JCT currently

provides estimates of the distributional consequences of certain changes in federal taxes, as it did when it analyzed Congressman Camp's comprehen- sive tax reform proposal (JCT 2014a). However, CBO does not provide cor-

responding estimates for changes in federal spending. CBO's recent reports on the distribution of federal taxes under current law (CBO 2014e) and the

distribution of federal taxes and spending under current law (CBO 2013d) described a number of conceptual complications and data limitations that arise in estimating the distributional impact of existing taxes and spending, and those problems are more acute when estimating the distributional impact of changes in taxes and spending. For example, distributional analy- sis of proposals ideally would incorporate macroeconomic analysis to cap- ture the partial shift in the burden of capital taxes from capital owners to workers stemming from changes in the amount of capital. However, CBO and JCT have not developed the models needed to conduct such "dynamic distributional analysis."

In my view, CBO and JCT should continue to enhance their capabilities in this area. Policy choices can have significant effects on the distribution of income as well as on total income, and outcomes that are quantified often receive greater attention in policy discussions than outcomes that are

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DOUGLAS W. ELMENDORF 129

not. Therefore, it would be very valuable for CBO and JCT to quantify the

effects of legislative proposals on both total income and its distribution.

ACKNOWLEDGMENTS I am grateful to Thomas Barthold, Wendy Edelberg, Glenn Hubbard, Jeffrey Kling, Donald Marron, Pam Moomau, Ben Page, and the editors for helpful comments on earlier drafts of this paper and

to many former colleagues at the Congressional Budget Office and on the staff

of the Joint Committee on Taxation for discussions that helped to form my

views on this topic. The views expressed here are my own and should not be attributed to any of those people or to any institution with which I was or am

currently affiliated.

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1 30 Brookings Papers on Economic Activity ; Fall 201 5

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