Additional Medicare Tax is 0.9% of Medicare wages above a filing-status threshold. It is not the 1.45% Medicare line on every stub.
The leftover most people miss at $400,000 is how far past $250,000 the joint line already is. Single / other is $200,000. Married filing separately is $125,000.
On $400,000 of Medicare wages:
- Joint: excess $150,000 → tax $1,350
- Single / other: excess $200,000 → tax $1,800
- Married filing separately: excess $275,000 → tax $2,475
- Joint at exactly $250,000 → tax $0
The $260,000 joint leftover is $90. Single leftover: $300,000 → $900. Two jobs under the withholding trigger: $190,000 + $45,000 → $315 if single.
Hub: United States calculators.
Employers withhold the extra 0.9% once that W-2 crosses $200,000. They do not look at your joint return. One $400,000 job should see the extra line. Two $200,000 jobs can withhold $0 extra on a joint return and you still owe $1,350 when you file. Estimate, not tax advice.
Direct answer: $400,000 joint → $1,350
- Joint threshold = $250,000
- Excess = $400,000 − $250,000 = $150,000
- Tax = 0.9% × $150,000 = $1,350
- Same wages, single = 0.9% × $200,000 = $1,800
- Same wages, MFS = 0.9% × $275,000 = $2,475
threshold = $250,000 joint · $125,000 MFS · $200,000 any other case
tax = 0.9% × max(0, Medicare wages − threshold)
Same $400,000, three statuses
| Status | Threshold | Excess | Tax |
|---|---|---|---|
| Married filing jointly | $250,000 | $150,000 | $1,350 |
| Single / other | $200,000 | $200,000 | $1,800 |
| Married filing separately | $125,000 | $275,000 | $2,475 |
Nearby joint wages
| Joint Medicare wages | Excess | Tax |
|---|---|---|
| $250,000 | $0 | $0 |
| $260,000 | $10,000 | $90 |
| $400,000 | $150,000 | $1,350 |
Base Medicare 1.45% is still on the whole wage. That is the FICA calculator, not this 0.9% add-on.
If one W-2 is $400,000, the extra 0.9% should start after that job crosses $200,000. Two jobs that each stay at $200,000 can withhold $0 extra and you still owe $1,350 on a joint return.
No. NIIT is a different statute on net investment income. This page is wages only.