Form 8959, Additional Medicare Tax, is used to figure the additional 0.9% percent Medicare tax on the portion of wages, self-employment, and railroad retirement income that exceeds a certain threshold.
That threshold is $250,000 for jointly filing couples, $125,000 for married couples filing separately, and $200,000 for everybody else.
We’ll automatically add Form 8959 to your return if your income exceeds the threshold amount for your filing status.