The form will tell you why you owe the extra tax. A common cause is an AGI over $250,000 when there is an extra tax on investment income.
To quote the instructions for form 8959:
"Additional Medicare Tax. A 0.9% Additional Medicare Tax applies to your Medicare wages, Railroad Retirement Tax Act (RRTA) compensation, and self-employment income above a threshold amount. The threshold amounts are.
Filing Status Threshold Amount
Married filing jointly $250,000
Married filing separately $125,000
Single $200,000
Head of household $200,000
Qualifying surviving spouse $200,000"
Thank you. I understand the calculation but I did not make over $200 and combined we did not make over 250 even with investments. The W-2 does not show over 250 either.
Check your w-2s for typos. The amount in box 6 should be .0145 percent of box 5. Sometimes rounding issues can generate the tax. Then look at your Earned Income worksheet. That will show you the total wages and compensation on your return. The 3rd column is the total.