Fill out Form 8959 (Additional Medicare Tax) online
Form 8959 is used to calculate the Additional Medicare Tax, a 0.9% surtax on earned income exceeding certain thresholds. This tax applies on top of the regular 1.45% Medicare tax withheld from wages and self-employment income.
How to fill out Form 8959 (Additional Medicare Tax)
Calculate Additional Medicare Tax on wages
In Part I, enter your total Medicare wages from all W-2 forms. Subtract the applicable threshold for your filing status. Multiply the excess by 0.9% to determine the additional tax on wages.
Calculate Additional Medicare Tax on self-employment income
In Part II, enter your self-employment income subject to Medicare tax. If your wages already exceeded the threshold, any self-employment income is fully subject to the 0.9% additional tax.
Calculate Additional Medicare Tax on railroad retirement compensation
In Part III, enter any railroad retirement (RRTA) compensation. Apply the same threshold and 0.9% rate to determine additional tax owed on this income.
Determine withholding credit and total additional tax
In Part IV, enter the Additional Medicare Tax already withheld by your employer (shown on your W-2). Subtract this from your total additional tax to determine the net amount owed or overpaid. Report the result on Schedule 2.
About Form 8959 (Additional Medicare Tax)
Who needs this form
Taxpayers whose Medicare wages, self-employment income, or railroad retirement compensation exceed $200,000 (single), $250,000 (married filing jointly), or $125,000 (married filing separately). Employers withhold the additional tax only on wages exceeding $200,000, regardless of filing status.
Where to submit
Attach Form 8959 to your Form 1040 or 1040-SR when filing your annual federal income tax return. The additional tax is reported on Schedule 2, line 23.
Source and content freshness
- Reviewed: 2026-02-24
- Filing deadlines may shift for weekends and holidays. Verify due dates with official instructions.
Common mistakes to avoid
- Not filing because your employer already withheld Additional Medicare Tax (you must still reconcile on the form)
- Using the wrong income threshold for your filing status (the $200,000 employer withholding threshold differs from the $250,000 joint filing threshold)
- Forgetting to include self-employment income when calculating total Medicare wages subject to the additional tax
- Not claiming credit for Additional Medicare Tax withheld by the employer on line 24 of Form 8959
Frequently asked questions
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Does my employer withhold enough Additional Medicare Tax if I am married filing jointly?
Not necessarily. Employers are required to withhold the 0.9% Additional Medicare Tax only on wages exceeding $200,000 per employee, regardless of filing status. If you are married filing jointly, the actual threshold is $250,000 of combined income, so you could owe additional tax or receive a credit depending on your combined wages and filing status.
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