Glossary
Additional Medicare Tax
Definition
The Additional Medicare Tax is an extra Medicare tax on high wages and self-employment income: 0.9% on wages over $200,0002026 · IRS of wages for withholding purposes. Employers don't match it, and final liability depends on filing status.
How Additional Medicare Tax works
Employers must withhold it once an employee's wages pass the threshold, regardless of filing status, so couples may be over- or under-withheld.
It is separate from the 3.8% net investment income tax, though both arrived together.
Why it matters to a firm
Two-earner high-income couples often owe more than was withheld, a classic April surprise.
| 2026 figure | Source |
|---|---|
| Additional Medicare Tax and withholding threshold: 0.9% on wages over $200,000 | IRS |
Questions about Additional Medicare Tax
Does my employer match it?
No.
Why might I owe more at filing?
Joint thresholds differ from the withholding threshold.
Does it apply to the self-employed?
Yes, on self-employment income above the threshold.
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Related terms: FICA · Net investment income tax
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