Also check your tax return to see if it includes Form 8959 with an amount on line 24 that is treated as income tax withholding.
The difference came from this page called Form 8959 that you can see when you print out or view your return. It comes from the amount that was withheld on Medicare taxes that they credit part of it to your tax payments. Don't understand it since ALL wages are subject to Medicare taxes, but at least now I can see where the extra credit in tax payments is coming from!
