Additional Medicare Tax Calculator (Form 8959)
Calculate the 0.9% Additional Medicare Tax on wages, self-employment income, and RRTA compensation above your filing-status threshold. Enter what your employer withheld to see whether you owe a balance or are due a credit on Form 8959.
- Medicare wages
- $220,000
- Self-employment income
- $0
- RRTA compensation
- $0
- Filing-status threshold
- $200,000
- Wages subject to Additional Medicare Tax
- $20,000
- Additional Medicare Tax (0.9%)
- $180.00
Additional Medicare Tax
$180.00Filing-Status Threshold
$200,000Employer Extra Withholding
$180.00How the Additional Medicare Tax Works
0.9% Surtax, Not Inflation-Indexed
Set by the ACA in 2013 under IRC §3101(b)(2) and never adjusted for inflation — the dollar thresholds have stayed the same for over a decade while wages have risen.
Filing-Status Thresholds
$250,000 MFJ, $125,000 MFS, $200,000 single/HoH/qualifying surviving spouse. Wages and SE income share one combined threshold; RRTA compensation is compared against the same threshold separately, not pooled with wages/SE.
Flat $200,000 Employer Withholding Trigger
Employers must withhold an extra 0.9% once a single employer's wages to you exceed $200,000 in the year — regardless of your actual filing status, spouse's income, or other employers.
Form 8959 Reconciliation
Part I–III compute the actual liability on wages, SE income, and RRTA compensation. Part IV compares that liability against what was withheld — the difference becomes a balance due or a credit on your Form 1040.
Filing-status thresholds (fixed by statute)
These dollar amounts have applied unchanged since the tax took effect in 2013 — Congress set them as flat statutory figures under IRC §3101(b)(2), not indexed to inflation like most other federal tax thresholds.
| Filing status | Threshold |
|---|---|
| Married filing jointly | $250,000 |
| Qualifying surviving spouse | $200,000 |
| Single | $200,000 |
| Head of household | $200,000 |
| Married filing separately | $125,000 |
Worked example
Single filer, $250,000 Medicare wages
$250,000 − $200,000 threshold = $50,000 subject wages. $50,000 × 0.9% = $450 Additional Medicare Tax. Since the employer's $200,000 withholding trigger matches the single threshold exactly here, the employer should have withheld the same $450 — no balance due if withholding matched.
Married couple, two employers, $150k each
Combined wages $300,000 vs the $250,000 MFJ threshold = $50,000 subject wages → $450 owed. But NEITHER employer individually withheld extra, because neither spouse's wages from a single employer exceeded $200,000. The couple owes the full $450 as a balance due on Form 8959 Part IV, often a surprise at filing time.
Frequently asked questions
What is the Additional Medicare Tax?
The Additional Medicare Tax is a 0.9% tax under IRC §3101(b)(2), added by the Affordable Care Act (effective 2013), on Medicare wages, self-employment income, and RRTA compensation above a filing-status threshold: $250,000 for married filing jointly, $125,000 for married filing separately, and $200,000 for single, head of household, and qualifying surviving spouse. Medicare wages and self-employment income share one combined threshold; RRTA compensation is compared against the same threshold separately (see the FAQ below on how RRTA is treated). Unlike the base 1.45% Medicare tax, it is not matched by employers and applies only to the employee/self-employed individual. It is reported and reconciled on Form 8959.
Are the Additional Medicare Tax thresholds indexed for inflation?
No. Unlike most federal tax thresholds, the Additional Medicare Tax thresholds are fixed by statute and have never been adjusted for inflation since they took effect in 2013. That means more filers become subject to the tax every year as wages rise — a form of real-terms "bracket creep" written directly into the law.
Why did my employer withhold Additional Medicare Tax when I don't owe it?
Employers must withhold an extra 0.9% on any single employer's wages that exceed $200,000 in a year — that withholding trigger is flat and does not know about your filing status or a spouse's income (IRC §3102(f)(1)). If you're married filing jointly with a combined threshold of $250,000, or if you have multiple employers each under $200,000 but the combined total pushes you over your actual threshold, the employer withholding can be too much or too little. Form 8959 Part IV reconciles the difference: over-withholding becomes a credit against your total tax; under-withholding becomes a balance due.
Does the Additional Medicare Tax apply to self-employment income?
Yes. Self-employed individuals owe the 0.9% Additional Medicare Tax on net self-employment earnings above the same filing-status thresholds, combined with any Medicare wages from a job. The tax is computed on Form 8959 Part II and there is no employer to withhold it — self-employed filers typically pay it through quarterly estimated taxes to avoid an underpayment penalty.
Is the Additional Medicare Tax deductible?
No. Unlike the 50% above-the-line deduction for the employer-equivalent half of self-employment tax, none of the 0.9% Additional Medicare Tax is deductible for income tax purposes — it's a straight surtax with no offsetting deduction.
Is RRTA compensation combined with wages and self-employment income for the threshold?
No — this is a common misconception. Per the <a href="https://www.irs.gov/instructions/i8959" target="_blank" rel="noopener noreferrer">IRS Instructions for Form 8959</a>, Medicare wages and self-employment income share ONE combined threshold (Parts I–II), but RRTA compensation (Part III) is compared against the SAME dollar threshold SEPARATELY — it is not pooled with wages or self-employment income. The instructions give this example: a railroad employee has $190,000 in wages and their spouse has $150,000 in RRTA compensation, filing jointly with a $250,000 threshold. Neither amount individually exceeds $250,000, so the couple owes $0 Additional Medicare Tax — even though the combined total ($340,000) exceeds $250,000. This calculator applies that rule.
Sources
Key Tax Terms
Additional Medicare Tax
An extra 0.9% Medicare surtax on earned income above $200,000 (single) or $250,000 (married filing jointly). Unlike regular Medicare tax, it is not matched by employers.
Medicare Tax
A 1.45% payroll tax on all wages with no income cap, matched by employers. High earners pay an Additional Medicare Tax of 0.9% on wages over $200,000 (single).
FICA
Federal Insurance Contributions Act taxes that fund Social Security (6.2%) and Medicare (1.45%). Both employees and employers pay FICA, totaling 15.3% on wages.
Self-Employment Tax
The combined Social Security (12.4%) and Medicare (2.9%) tax paid by self-employed individuals — effectively both the employee and employer shares of FICA, totaling 15.3%.
W-2
A tax form employers send to employees each year reporting wages earned and taxes withheld, including federal income tax, Social Security, and Medicare.
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