Gross Income and Exclusions

Sam and Sue are married and age 65.  Sam has a full time job that pays $80,000 and Sue's full time job pays $85,000.  They have worked since age 16 and are planning on keeping their jobs and signing up for social security when they each reach age 66.   An friend of the couple heard that social security benefits might be taxable and suggested that the couple file for divorce to get more money from social security and also avoid taxes on social security.  The statement from social security indicated that Sam would receive $1,800 per month if he waits until full retirement. Sue can't find her letter, but over her working career, she made as much and sometimes more than Sam did.    What is their best tax planning strategy?