Why the wage threshold is not the withholding threshold
Your filing-status threshold determines the 0.9% liability on your return. Each employer instead starts withholding after paying you $200,000 of Medicare wages, regardless of marriage or another job. Enter every employer separately. Two $150,000 jobs do not produce the same withholding as one $300,000 job.
The result separates tax on wages from tax on self-employment income, then compares their sum with derived employer withholding. A positive balance is an Additional Medicare shortfall; a negative balance is overwithholding credited through the return. It is not a prediction of the whole return refund.
Household examples: identical income can yield different balances
| Situation | Liability | Derived withholding | Balance |
|---|---|---|---|
| MFJ: $150,000 + $175,000 wages, separate spouses | $675 | $0 | $675 to cover |
| MFJ: one $260,000 job; spouse earns $0 | $90 | $540 | $450 overwithheld |
| Single: two $150,000 employers | $900 | $0 | $900 to cover |
| Single: one $300,000 employer | $900 | $900 | $0 |
The first example reproduces the wages and $675 liability in IRS Form 8959 instructions, Example 5. The other rows apply the same statutory thresholds to illustrate the independent withholding rule.
Use the right W-2 and Schedule SE amounts
Use W-2 box 5 Medicare wages, not box 1 income-tax wages. For self-employment, enter the positive Schedule SE line 6 amount after the applicable Schedule SE calculation, not business revenue or Schedule C profit. Married filing jointly includes both spouses; other filing statuses ignore the spouse inputs.
For wages, taxable excess is max(0, wages − threshold). For self-employment, the remaining threshold is max(0, threshold − wages). Positive self-employment income above that remainder receives the additional 0.9%. A spouse’s loss does not offset the other spouse’s positive SE tax base here.
| Filing status | Liability threshold |
|---|---|
| Married filing jointly | $250,000 |
| Married filing separately | $125,000 |
| Single, head of household, qualifying surviving spouse | $200,000 |
What this reconciliation does not calculate
Actual withheld amounts can differ from the derived estimate because of payroll adjustments or errors; use actual W-2 information and Form 8959 to file. The tool supports two employers per spouse. Do not aggregate additional employers into a row: that would change the $200,000 withholding test. Railroad retirement compensation (RRTA), church/farm optional Schedule SE methods, full income-tax liability, and estimated-payment penalties are outside this tool.
The Additional Medicare Tax is not the regular 1.45% Medicare tax or the Schedule SE 2.9% Medicare component. Employers do not match the extra 0.9%, and it is not included in the deductible half of regular self-employment tax.
Official sources
Rules rechecked October 4, 2026. Source versions and calculation scope are stated above.