Additional Medicare Tax on Wages

Above certain thresholds, your paycheck faces a 0.9% Additional Medicare Tax — a surtax on earned income separate from the 3.8% investment-income surtax. Unlike the regular 1.45% Medicare tax, which employer and employee split equally, this additional 0.9% is borne entirely by the employee (or self-employed person) and is one of the stealthiest tax increases to hit middle and upper-middle-income earners since 2013.

The two-part structure: employee and employer components

Most people think of Medicare tax as the flat 1.45% withheld from paychecks, matched by the employer. Starting in 2013, Congress added a second, surtax layer: the Additional Medicare Tax (sometimes called the Unearned Income Medicare Contribution Tax, or UIMCT, though that name is misleading because it applies to earned income for individuals).

The employee version is straightforward: if your wages exceed $200,000 (single) or $250,000 (married filing jointly) in a calendar year, you owe an extra 0.9% Medicare tax on the amount above the threshold. Your employer is required by law to withhold this tax once your year-to-date wages cross the threshold.

The employer version is less well known: employers also owe a 0.9% Medicare tax on wages, but with no threshold. Any employer paying more than $250,000 in wages in a year owes 0.9% Medicare tax on the amount over $250,000, regardless of individual employee thresholds. This creates a dual-layer surtax structure that makes the total Medicare tax rate on high-wage payrolls effectively 2.35% to the employee and 2.35% to the employer (1.45% base + 0.9% additional).

Why the thresholds create a marriage-penalty trap

The thresholds are not indexed for inflation; they’ve remained fixed since 2013. As nominal wages have risen, more and more two-income households have found themselves subject to the tax.

Consider a married couple, each earning $150,000, filing jointly. Combined earned income is $300,000, exceeding the $250,000 threshold by $50,000. They owe 0.9% × $50,000 = $450 in Additional Medicare Tax. If they were each filing as single (either unmarried or in a state with common-law marriage), each would fall below the $200,000 threshold and owe nothing. The surtax effectively penalizes marriage at high incomes.

The tax also creates coordination issues for dual-income households. If spouse A earns $180,000 and spouse B earns $100,000, the $280,000 combined income exceeds the $250,000 threshold by $30,000. Both spouses’ employers, if working for separate employers, withhold based on each individual’s wages. Neither may cross the $200,000 single threshold at their respective employer, so neither employer withholds the Additional Medicare Tax. At year-end, the couple discovers they owe $270 (0.9% × $30,000) that wasn’t withheld. They must either pay it with their return or amend Form W-4 across both employers to increase withholding.

What income counts and what doesn’t

Earned income subject to the tax:

• Wages and salaries (W-2 income)
• Bonuses and commissions
• Net self-employment income (after deducting the self-employment tax deduction)
• Wages paid by employers to officers and directors, even if de facto passive

Earned income NOT subject to the tax:

• Pension and annuity distributions (though earned income from current employment does count)
• Distributions from qualified retirement plans like 401(k)s, IRAs, or Roth IRAs (these are not earned income)
• Stock options and restricted stock awards at grant (unless immediately taxable; the bargain element is treated as wages)

Investment income specifically excluded:

• Capital gains from sale of securities or real property
• Dividend income from stocks or mutual funds
• Interest on bonds or savings accounts
• Rental income from real estate (passive income)
• Income from partnerships or S-corporations allocated as profit (unless it’s guaranteed payments to a partner, which are treated as self-employment income)
• Income from trusts or estates allocated to beneficiaries

This distinction is crucial: the Additional Medicare Tax on Wages is entirely separate from the Net Investment Income Surtax. A high-income individual can owe both: 0.9% on wages above $200K, and 3.8% on investment income above the threshold. The two surtaxes apply to different income bases and use the same MAGI thresholds purely as a coincidence of legislative drafting.

Self-employed individuals and the withholding gap

For W-2 employees, the employer handles withholding once year-to-date wages exceed the threshold. But for self-employed people, there is no employer to withhold. Instead, self-employed individuals compute their net self-employment income (net profit after the self-employment tax deduction), and if that income combined with any W-2 wages exceeds the threshold, they owe Additional Medicare Tax.

The self-employed person must account for this tax through estimated tax payments, usually in four quarterly installments. Many self-employed filers are caught off-guard: they may not have withheld enough in their Q1–Q3 estimates, and by Q4, they realize they owe Additional Medicare Tax. Some use Form 2210 to annualize their income and justify lower early-year payments, which can reduce underpayment penalties.

Example: You are a self-employed consultant, married filing jointly. In January, you estimate net profit of $150,000 for the year. You make quarterly estimated tax payments for federal income tax and self-employment tax, but you didn’t account for Additional Medicare Tax (assuming your spouse had $100,000 W-2 wages, your combined threshold is $250,000, and $150,000 + $100,000 = $250,000, barely at the line). Then your business is successful; actual net profit is $200,000. Combined with your spouse’s wages, total earned income is $300,000. You now owe an additional 0.9% × ($300,000 - $250,000) = $450 in Additional Medicare Tax, plus interest and possible penalties for underpayment.

The filing-status marriage-penalty-widows gap

The thresholds differ by filing status: $200K single, $250K married filing jointly, $125K married filing separately. The $125K threshold for married filing separately is punitive — if a married couple each earns $150,000 but files separately, each individual crosses the $125K threshold and owes tax on $25,000 of income (0.9% × $25,000 × 2 spouses = $450 total). Filing separately to separate assets or income (e.g., in a high-conflict marriage) comes at a steep surtax cost.

Equally tricky: if you are a surviving spouse in the year of your spouse’s death, you may have a complex household (e.g., filing as “married filing jointly” in the year of death, then “head of household” the following year). The threshold shifts, and if you had combined income near the $250K line during the joint return year, you may owe surtax in the year of death; in the next year, the same income amount may fall below the new “head of household” threshold (which Congress has not formally defined in statute, though the IRS has issued guidance suggesting it may align with the single threshold).

Employer withholding and compliance

Employers must withhold Additional Medicare Tax from employees’ wages once year-to-date wages exceed the employee’s threshold. However, employers can only track individual employee thresholds if they receive accurate information (via Form W-4). If an employee is undeclared or has multiple employers, the system breaks down.

If an employee has two employers and each employer’s payroll system is independent, neither may cross the employee’s $200K threshold. In that case, no Additional Medicare Tax is withheld by either employer, and the employee has a large bill at tax time. The employee can file an amended W-4 with each employer to increase withholding or claim a special status, but many don’t, leading to surprise tax bills.

Employers report employees’ Medicare tax withholding on Box 6 of the Form W-2. The IRS reconciles this against what the employee reports on their tax return. If there’s a mismatch, the IRS will assess the Additional Medicare Tax (plus interest and penalties) or issue a refund if too much was withheld.

The political stalemate and no indexation

The Additional Medicare Tax has been a source of ongoing political debate since its enactment in 2010 (effective 2013) as part of the Affordable Care Act. Opponents argue it is a hidden tax that disproportionately hits upper-middle-class earners in high-cost-of-living areas; the fact that the thresholds are not indexed for inflation means more people fall into the tax year after year as nominal wages rise.

Congress has periodically considered indexing the thresholds to inflation (or raising them outright) but has not acted. As a result, the surtax’s reach expands silently. A household in San Francisco or New York earning “just” $250,000 in household income — a figure that feels middle-class to many high-earners in those cities — now faces a surtax on every dollar above the threshold.

Planning and avoidance strategies (limited)

Unlike the Alternative Minimum Tax, which offers credits and deferral mechanisms, the Additional Medicare Tax on Wages offers little planning opportunity:

1. Timing and deferral — If you expect a very high-income year, you could attempt to defer some bonus or commission to the following year, though employers usually control timing.
2. Income splitting — For self-employed couples, structuring work as separate S-corporations or partnerships and managing distributions can sometimes lower individual MAGI (though the economics may not justify the complexity).
3. Retirement contributions — Maximizing 401(k), SEP-IRA, and Solo 401(k) contributions reduces net self-employment income; but these strategies have annual caps and are available to all taxpayers, not just those in the surtax range.

Most high-income earners simply accept the surtax as a cost of earning above the threshold and factor it into their gross-income expectations.

Integration with other taxes and policy

The Additional Medicare Tax on Wages is separate from:

• The Net Investment Income Surtax (3.8% on investment income) — different income bases, both applicable simultaneously
• The Alternative Minimum Tax (though both can apply in the same year, they use different mechanics)
• Regular Medicare tax (1.45% base, which continues at all income levels)

For high earners, the combined marginal tax burden can exceed 50% when combining federal income tax (top bracket), state income tax, Net Investment Income Surtax, and Additional Medicare Tax on Wages. This concentration of tax at the top end was a design choice by Congress in the 2010 Affordable Care Act to fund the law’s coverage expansions.

See also