Additional Medicare Tax Calculator
Find the 0.9 percent surtax on wages and self-employment income above your filing status threshold.
What it does
Medicare tax has two layers. The base layer is 1.45 percent on all wages, matched by the employer. The additional layer is 0.9 percent on wages and self-employment income above a threshold that depends on filing status. Unlike the base layer, the additional tax has no employer match. The worker pays the whole 0.9 percent.
The thresholds are fixed in law and are not indexed for inflation. A single filer crosses at $200,000, a married couple filing jointly at $250,000, and a married person filing separately at $125,000. Head of household uses the same $200,000 threshold as single. These are not tax brackets: the 0.9 percent applies only to the amount above the line, not to all income.
Employers must withhold the additional tax once wages from that employer pass $200,000 in a year. They do not know the employee's filing status or the spouse's wages, so withholding can be too low or too high. A single filer with two jobs can have each employer stay under $200,000 while the combined total is well above it. A married couple filing jointly can have one spouse cross $200,000 and face withholding even though the household stays under $250,000.
Self-employment income enters the calculation too. Net earnings are combined with wages to measure the distance above the threshold, and the 0.9 percent applies to that combined excess. Form 8959 handles the arithmetic: it adds Medicare wages and self-employment income, subtracts the threshold, computes the tax, and credits any withholding already taken.
This page gives a planning estimate. It uses the threshold for your status, adds wages and self-employment income, computes the 0.9 percent tax, and subtracts the standard employer withholding on wages above $200,000. It does not compute the base 1.45 percent Medicare tax, the Social Security tax, or the self-employment tax deduction. Use it to see whether you may owe a balance, then confirm the final figure on Form 8959.
How to use
- Choose your filing status so the correct threshold is used.
- Enter total Medicare wages from all W-2 jobs, not just one employer.
- Enter net self-employment earnings as reported for Form 8959.
- Read the excess over the threshold and the 0.9 percent tax.
- Compare the tax with the withholding shown to see whether a balance is likely.
- Report the final numbers on Form 8959 and carry them to Form 1040.
Formula
- 0.9 %
- The Additional Medicare Tax rate.
- Wages
- Medicare wages from Form W-2 box 5, all jobs combined.
- SE income
- Net self-employment earnings used on Form 8959.
- Threshold
- $200,000 single, $250,000 joint, $125,000 married filing separately.
- $200,000
- The wage level at which employers must begin withholding, regardless of status.
The threshold is compared with combined wages and self-employment income, but employer withholding is triggered by wages alone at $200,000 per employer. That mismatch is why a refund or a balance can appear even when the tax was withheld. Form 8959 uses net self-employment earnings after the 92.35 percent adjustment, so enter the figure that belongs on that form rather than gross receipts. Married filing separately has a $125,000 threshold, which means a couple can owe more tax when they file separately than when they file jointly. The thresholds are set by statute and do not rise with inflation.
Worked example
Example: single filer with $180,000 of wages and $60,000 of self-employment income
A single filer has $180,000 in Medicare wages and $60,000 in net self-employment earnings.
- Combined income: $180,000 + $60,000 = $240,000.
- Threshold for single: $200,000.
- Excess: $240,000 - $200,000 = $40,000.
- Additional Medicare Tax: $40,000 x 0.009 = $360.00.
- Employer withholding: wages of $180,000 are below $200,000, so withholding is $0.00.
- Balance at filing: $360.00 - $0.00 = $360.00 due.
- The base 1.45 percent Medicare tax is separate and is not included here.
Reference table
| Filing status | Threshold | Tax on $300,000 | Tax on $400,000 |
|---|---|---|---|
| Single or head of household | $200,000 | $900.00 | $1,800.00 |
| Married filing jointly | $250,000 | $450.00 | $1,350.00 |
| Married filing separately | $125,000 | $1,575.00 | $2,475.00 |
Limits
- Does not compute the base 1.45 percent Medicare tax or the 3.8 percent net investment income tax.
- Uses one combined wage figure, so multi-employer withholding needs a manual check.
- Ignores the self-employment tax deduction and other adjustments that change net SE earnings.
- State taxes and other withholding are outside the scope of this estimate.
Common mistakes
- Applying 0.9 percent to all wages instead of only the excess above the threshold.
- Using the joint $250,000 threshold when filing separately.
- Assuming employer withholding will always cover the tax when there are multiple jobs.
- Entering gross self-employment receipts instead of net earnings.
- Confusing the 0.9 percent Medicare surtax with the 3.8 percent net investment income tax.
Try it yourself
Quick checks. Answers sit tucked under each question.
A single filer has $250,000 of wages and no self-employment income. What is the Additional Medicare Tax?
Excess = $250,000 - $200,000 = $50,000. Tax = $50,000 x 0.009 = $450.00. Withholding is $50,000 x 0.009 = $450.00, so the balance is $0.00.
A joint filer has $220,000 of wages and $50,000 of self-employment income. What is the tax?
Combined income is $270,000. Excess over $250,000 is $20,000. Tax = $20,000 x 0.009 = $180.00. Withholding is $20,000 x 0.009 = $180.00, so the balance is $0.00.
A married filing separately filer has $140,000 of wages. What is the tax and balance?
Excess over $125,000 is $15,000. Tax = $15,000 x 0.009 = $135.00. Wages are below $200,000, so withholding is $0.00 and $135.00 is due.
Questions
What is the Additional Medicare Tax?
A 0.9 percent tax on wages and self-employment income above a filing status threshold. It is paid by the worker, with no employer match.
What are the thresholds?
$200,000 for single and head of household, $250,000 for married filing jointly, and $125,000 for married filing separately.
Do employers withhold it?
Yes, once wages from that employer exceed $200,000 in a year. The employer does not adjust for filing status or a spouse's income.
Is it the same as the 3.8 percent net investment income tax?
No. The 0.9 percent tax applies to wages and self-employment income. The 3.8 percent tax applies to net investment income and has its own threshold rules.
Why do I owe a balance if tax was withheld?
Withholding is based on each employer's wages above $200,000, not on your combined income or filing status. Multiple jobs or self-employment can leave a gap.
Where is it reported?
On Form 8959, which is attached to Form 1040. The tax is included in total tax on the return.