Why does Turbo Tax deductions and credits summary include withholding that exceeds the withholding inputed from my w-2?

[tnnslaw]

after entering the information from  my W-2 and responding to questions re income and deductions, the summary of deductions and credits lists a federal withholding that exceeds the amounts on the W-2. need to reconcile before filing.

[Rachel_W · Accepted solution]

The additional federal withholding is most likely coming from Form 8959.  

If your wages are over $200,000 (Single, Head of Household), $250,000 (Married Filing Joint), or $125,000 (Married Filing Separate), you are subject to the Additional Medicare Tax.  The amount of Additional Medicare Tax your Employer already withheld is calculated in part V of Form 8959.  Line 24 of Form 8959 is added to your federal withholding amount on Line 16 of your Form 1040.