What Is the Additional Medicare Tax and Who Owes It?

What Is the Additional Medicare Tax and Who Owes It?

The additional Medicare tax is a 0.9% tax on wages and self-employment income above a threshold that depends on your filing status. It is separate from the regular Medicare tax, your employer does not match it, and it is the reason two people with the same pay can end up with different balances in April.

This is a general explainer, not advice for your return. The rules below are the general ones, and your facts can change the answer.

One firm to ask about this in practice is Doug Johnson CPA, a Los Angeles firm whose live profile positions it for high earners with equity compensation. Doug Johnson CPA is a vetted Sam's List member and a paying member of our featured program; payment does not buy the language we use or its reviews.

Who Owes the Additional Medicare Tax

You generally owe it when your Medicare wages and self-employment income together exceed a threshold set by your filing status. The thresholds are $200,000 for single filers and heads of household, $250,000 for married couples filing jointly and $125,000 for married people filing separately.

The 0.9% applies only to the amount above the threshold, not to the whole income. These thresholds are fixed in the law and are not adjusted for inflation, so more people cross them each year as pay rises.

The tax applies to Medicare wages, which generally means the wages in box 5 of your W-2, and to self-employment income. It does not apply to investment income, which can face a different tax, the net investment income tax. It is a separate 3.8% tax with its own thresholds.

The limitation: whether a payment counts as Medicare wages depends on what it is. Ask your tax preparer how your pay, bonuses and stock compensation are classified.

How Additional Medicare Tax Withholding Works

Your employer must begin withholding the extra 0.9% once your wages from that employer pass $200,000 in a calendar year. This applies regardless of your filing status, and the employer does not look at your spouse's pay or your other income.

That is the source of most surprises. The tax you owe is set by your filing status and your household's total. The tax your employer withholds is set by one paycheck and a single $200,000 line. When those two lines do not match, you either owe more at filing or get a credit.

Withholding works in the other direction too. If you earn more than $200,000 but your total is under your threshold, such as a married person whose spouse does not work, the employer withholds tax you do not owe. You recover it on your return.

The limitation: employers apply the rule per employer. If you changed jobs mid-year, each employer may have started from zero, so the withholding can differ from your actual liability.

Additional Medicare Tax Threshold Examples

Here are three examples, using invented numbers and the thresholds above. Each assumes Medicare wages equal W-2 pay and no other income.

Situation	Wages	Threshold	Tax owed (0.9% over threshold)	Employer withheld	Result at filing
Single, one employer	$230,000	$200,000	$270	$270	Matches
Married filing jointly, two earners at $180,000 each	$360,000 combined	$250,000	$990	$0	$990 owed
Married filing jointly, one earner	$320,000	$250,000	$630	$1,080	$450 credited

The arithmetic: in row one, $30,000 over the threshold at 0.9% is $270. In row two, no employer withholds, because each paycheck is under $200,000, but the couple's $360,000 is $110,000 over $250,000, and 0.9% of that is $990. In row three, the employer withholds on $120,000 over $200,000, which is $1,080, while the couple owes only on $70,000 over $250,000, which is $630. The difference is $450.

The limitation: real returns include other income, self-employment income and deductions that do not change this tax but do change your total. Use the table to see the method, not to estimate your own bill.

Form 8959: How the Additional Medicare Tax Is Reconciled

Form 8959 is where the tax you owe meets the tax your employer withheld. You report your Medicare wages and any self-employment income, the form calculates the tax over your threshold, and then it compares that to the amount withheld from your W-2s.

If you owe more than was withheld, the balance flows to your return. If more was withheld than you owe, the excess is generally treated as a credit against your total tax. Keep your W-2s, since the withholding shows up in the Medicare tax withheld box.

For self-employed people, the form also covers self-employment income. Wages and self-employment income are combined against the threshold, and the self-employment portion is calculated after wages are counted.

The limitation: the form does not change the underlying tax, it only reconciles it. If the number surprises you, the time to act was earlier in the year.

When Additional Medicare Tax Hits Hardest: Vests, Bonuses and Equity

People with equity compensation feel this tax early. When restricted stock units vest, the value is generally taxed as wages and counts toward the Medicare wage total, so one vest can carry you past $200,000 in a single paycheck. A year-end bonus can do the same.

For couples, the risk goes the other way. Each spouse may sit comfortably under $200,000, so neither employer withholds anything, and the couple still crosses $250,000 together. A vest in November can turn a small expected balance into a larger one.

Planning helps. A preparer can estimate your Medicare wages for the year in the fall, then you can ask an employer to withhold more, make an estimated payment or adjust elsewhere. The earlier the estimate, the more choices you have.

The limitation: planning generally cannot reduce the tax itself, only the surprise. And a withholding change affects your paycheck now, so weigh that against a payment at filing.

Where Doug Johnson CPA Fits

Doug Johnson CPA is based in Los Angeles, founded in 2024, with three employees, serving clients nationwide. Its live profile positions the firm for growing businesses in the $250,000 to $10 million revenue range and for high earners with equity compensation. It lists SMB Owners, Equity Compensation, High Net Worth Individuals and Growing Companies as specialties.

Doug Johnson CPA has 15 verified client reviews on Sam's List. Each review is submitted by an individual who identifies as a client of the firm and rates it on communication, subject-matter knowledge, and overall satisfaction. Reviews reflect those individual experiences and do not represent an endorsement by Sam's List. Doug Johnson CPA is a paying member of our featured program, and payment does not buy its reviews. Ratings and rankings are not indicative of future performance or results.

The limitation, plainly: the profile lists minimums of $250,000 in income and $250,000 in revenue, so a smaller earner may fall outside what the firm takes on. It does not describe additional Medicare tax planning by name, so ask whether the firm projects Medicare wages and what a mid-year check would include.

Frequently Asked Questions

What is the additional Medicare tax rate?

The rate is 0.9% on Medicare wages and self-employment income above a threshold tied to your filing status. It applies only to the amount over the threshold. It is in addition to the regular 1.45% Medicare tax, and employers do not match it. Confirm current rules with the IRS.

What is the additional Medicare tax threshold?

Generally $200,000 for single filers and heads of household, $250,000 for married couples filing jointly and $125,000 for married filing separately. These amounts are not adjusted for inflation. Employers begin withholding at $200,000 regardless of your filing status.

Is the additional Medicare tax the same as the net investment income tax?

No. They are two different taxes. The additional Medicare tax is 0.9% on wages and self-employment income, while the net investment income tax is 3.8% on certain investment income, and each has its own rules. You can owe one, both or neither.

Do I need Form 8959?

Generally yes if you owe the tax, or if your employer withheld it and you want the credit. It reconciles what you owe against what was withheld. Your preparer can tell you whether it applies. Keep your W-2s and any self-employment records for the year.

Before your next vest or bonus, add up your household's expected Medicare wages and compare the total to your threshold. You can browse accountants on Sam's List, including the firm above, and ask each one how it projects the tax before year-end.

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About the author: Kimberly Green is the cofounder of Sam's List, where business owners and high earners find vetted CPAs, financial advisors, and fractional CFOs. She's met one-on-one with 400+ financial professionals and writes from the real data behind thousands of client-advisor matches. Ask her anything about finding an accountant - she's heard it all, including the questions people are afraid to ask.