Former boss withheld my husbands paychecks from nov'09 until feb '10. Then he included them on the w2 form and said that this had to be because he actually drew the checks in 09 even though he was holding them back at the time.

Legally, can I demand that the w2 form be amended to reflect the actual dates I received the income? It will make a substantial difference to our tax return.

As a cash basis taxpayer, you are taxed based on when you RECEIVE the income, not when the check is drafted.

You have a case to take to the IRS to force the employer to change the W-2.