What is the Additional Medicare Tax?
The Additional Medicare Tax — sometimes called the 0.9% Medicare surtax — applies to wages that exceed a filing-status-based threshold. It sits on top of the regular 1.45% Medicare tax, pushing the effective Medicare rate to 2.35% on wages above the threshold.
Unlike the regular Medicare tax, the Additional Medicare Tax has no employer match — the employee pays the full 0.9%. It was enacted by the Affordable Care Act (ACA Section 1411) and applies to wages, railroad retirement compensation, and self-employment income.
These thresholds are statutory. Unlike tax brackets, the Additional Medicare Tax thresholds do not adjust for inflation. They have remained unchanged since 2013 and will stay the same until Congress changes the law.
Thresholds by filing status
The Additional Medicare Tax threshold depends on your filing status: $200,000 for single filers and $250,000 for married filing jointly. Combined wages above these thresholds are subject to the surtax.
| Filing Status | Threshold |
|---|---|
| Single | $200,000 |
| Married Filing Jointly | $250,000 |
| Married Filing Separately | $125,000 |
| Head of Household | $200,000 |
The MFS threshold is $125,000 — exactly half of the MFJ threshold. Married couples filing separately hit this much sooner, making MFS particularly expensive for high earners.
The multi-employer trap
Here is the problem: employers only withhold the 0.9% Additional Medicare Tax when your wages from that single employer exceed $200,000. They have no visibility into what your other employers pay you. A second job that pushes you over the threshold creates a tax bill that neither employer accounts for.
Two jobs paying $150,000 each means $300,000 in combined wages — $100,000 above the single-filer threshold. But neither employer withholds a penny of Additional Medicare Tax because each is under $200,000.
The result: ($300,000 - $200,000) x 0.9% = $900 owed at filing that you did not know about.
This is the single most common tax surprise for multi-job filers earning $200K+. No employer warns you. No withholding is taken. You find out in April.
Common two-job scenarios (Single filer, $200,000 threshold):
| Job 1 | Job 2 | Combined | Above Threshold | Additional Medicare Tax |
|---|---|---|---|---|
| $120,000 | $90,000 | $210,000 | $10,000 | $90 |
| $150,000 | $150,000 | $300,000 | $100,000 | $900 |
| $130,000 | $130,000 | $260,000 | $60,000 | $540 |
| $180,000 | $120,000 | $300,000 | $100,000 | $900 |
How to calculate your liability
The formula is straightforward: take your combined wages, subtract your filing-status threshold, and multiply by 0.9%.
Worked example
Filing status: Single, threshold: $200,000
Job 1: $175,000
Job 2: $85,000
Combined wages: $260,000
Amount above threshold: $260,000 - $200,000 = $60,000
Additional Medicare Tax: $60,000 x 0.9% = $540
Regular Medicare from both jobs: $260,000 x 1.45% = $3,770
Total Medicare tax: $3,770 + $540 = $4,310
Neither employer withholds any of the $540 — Job 1 is under $200,000 and Job 2 is well under. The full amount is due at filing unless you prepay.
Form 8959
If you owe Additional Medicare Tax, you must file Form 8959 with your return. This form reconciles the total Additional Medicare Tax you owe against any Additional Medicare Tax that was already withheld by an employer.
Even if one employer did withhold the 0.9% — because your wages from that employer alone exceeded $200,000 — you still file Form 8959 to compute the net amount. Any withholding credit from that employer reduces what you owe.
Example: partial withholding
Job 1: $220,000 — employer withholds 0.9% on $20,000 = $180
Job 2: $80,000 — employer withholds $0
Total owed: ($300,000 - $200,000) x 0.9% = $900
Net due on Form 8959: $900 - $180 = $720
How to prepay
You have two options to avoid a lump-sum bill at filing.
1. Increase W-4 withholding
Add extra withholding on Step 4(c) of your W-4. Divide the expected Additional Medicare Tax by the number of remaining pay periods. For example, if you owe $540 and have 24 biweekly pay periods left, add $23 per paycheck.
2. Quarterly estimated payments
Include the Additional Medicare Tax in your quarterly estimated payment calculation using Form 1040-ES. Spread the liability across the remaining quarterly due dates.
Most people find W-4 adjustments easier than quarterly payments. MultiW2 calculates the exact per-paycheck amount for each job so you can update your W-4 once and stop thinking about it.
How MultiW2 catches the trap
MultiW2 adds up all your W2 wages, checks against your filing status threshold, and shows the Additional Medicare Tax liability. It warns you when combined income triggers the surtax — and shows the per-paycheck W-4 adjustment to prepay it. Estimate your tax liability to see whether you owe the surtax.
Tax data shown reflects projected 2026 figures based on CPI-adjusted 2025 published IRS rates.