TurboTax is calculating an Additional Medicare Tax of 0.9% even though our income does not exceed the threshold of $250k for married filing jointly. Can I correct this?

[super-eo]

I have reviewed the tax forms and there is nothing indicating our income would warrant the additional Medicare tax, but this has been calculated and deducted from the refund amount nonetheless. I would think the forms would clearly outline the math that results in this additional tax charge, but it's not there and leads me to question the TurboTax guarantee of 100% accuracy.

[DoninGA]

Go back to your W-2 entry.   Makes sure that the Medicare taxes withheld in box 6 are exactly 1.45% of the amount of the Medicare wages in box 5.  Even if the amount is only 1 or 2 cents more than 1.45% this will cause the program to request the Form8959.  Reduce the amount of Medicare taxes withheld by removing a few cents from the taxes withheld.