stay tuned... we're still pursuing a Michigan tax answer to a related issue.
 
IRS Addresses Automotive Buyout Misinformation on Withheld Taxes
 
The Internal Revenue Service moved today to address misinformation regarding automotive employee buyouts. Reports have recently appeared in the media that erroneously state that automotive employee buyout payments, some dating as far back as 2006, should not have been subject to FICA and Medicare withholding.
These reports have further indicated that individuals should file claims with the IRS for the refund of the money that was withheld. While the IRS cannot speak to any particular company's or particular employee's tax situation, the law regarding such payouts is clear .

As noted by IRS Publication 15, payments given to employees as an incentive to cancel an employment contract and relinquish employment rights are taxable and subject to employment taxes and withholding. Individuals should not be misled into filing refund claims for FICA and Medicare withholdings because under these circumstances former employees would not be entitled to such refunds.
 
Excerpt form IRS Publication 15, Section 5 , page 10 (emphasis added):
"Wages subject to federal employment taxes generally include all pay that you give to an employee for services performed. The pay may be in cash or in other forms. It includes salaries, vacation allowances, bonuses, commissions, and fringe benefits. It does not matter how you measure or make the payments. Amounts an employer pays as a bonus for signing or ratifying a contract in connection with the establishment of an employer-employee relationship
and an amount paid to an employee for cancellation of an employment contract and relinquishment of contract rights are wages subject to social security, Medicare, and federal unemployment taxes and income tax withholding. Also, compensation paid to a former employee for services performed while still employed is wages subject to employment taxes."
 
Luis D. Garcia
IRS Media Relations
 

The misunderstanding seems to find its source in an in-house GM memo addressed to those employees receiving the 2006 buyout who were drawing Social Security before reaching normal retirement age. 

The memo was intended to address the issue that these buy-out funds, reported on Form W2 were not "earned income" that would affect these specific employees and their exposure to repayment of excess Social Security benefit payments.   The payments were/are subject to Social Security and Medicare
withholding but would not cause the loss of Social Security benefits to anyone age 62 or older (60 as a widow/widower). 

Thanks to our own Michigan Chapter officers Byron Kuxhaus and Glen Mitchel for research and dogged pursuit of a correct answer to this issue.