Additional Medicare Tax
An extra 0.9% Medicare surtax on earned income above $200,000 (single) or $250,000 (married filing jointly). Unlike regular Medicare tax, it is not matched by employers.
The Additional Medicare Tax is a 0.9% surtax that applies to earned income (wages, compensation, and self-employment income) above certain thresholds. For single filers the threshold is $200,000, for married filing jointly it is $250,000, and for married filing separately it is $125,000.
This tax was introduced by the Affordable Care Act in 2013. Employers are required to begin withholding the additional 0.9% once an employee's wages exceed $200,000 in a calendar year, regardless of filing status. This means some married couples may need to adjust on their return.
The Additional Medicare Tax is calculated on Form 8959, which is filed with your tax return. There is no employer match for this surtax. Combined with the base 1.45% employee Medicare tax, high earners effectively pay 2.35% in Medicare taxes on income above the threshold.
How it works
The Additional Medicare Tax is a 0.9% surtax layered on top of ordinary Medicare tax, applying to earned income above set thresholds: $200,000 for single filers, $250,000 for married filing jointly, and $125,000 for married filing separately. It was introduced by the Affordable Care Act starting in 2013 and applies to wages, other compensation, and self-employment income once the relevant threshold is crossed.
Employers are required to begin withholding the extra 0.9% automatically once a single employee's wages exceed $200,000 within that employer, regardless of the employee's actual filing status or a spouse's income — the employer has no way to know about a household's combined situation. You reconcile the correct amount on Form 8959 when you file, which can mean married couples with two moderate incomes owe additional tax at filing time even though neither employer withheld anything, or a single filer with one job gets the withholding right automatically.
There is no employer match for this surtax, unlike the base 1.45% Medicare tax, so the full 0.9% comes out of the employee's own pay once the threshold is hit. Combined with the base employee Medicare rate of 1.45%, a high earner's total Medicare-related withholding on income above the threshold reaches 2.35%. Self-employed taxpayers owe the same 0.9% surtax on self-employment income above the thresholds, calculated through Form 8959 alongside their regular self-employment tax, and it is easy to underpay this if quarterly estimates were based only on the base Medicare rate.
Example: Additional Medicare Tax on a single filer
A single filer earns $230,000 in wages for the year, which is $30,000 above the $200,000 threshold for single filers.
The employer withholds the extra 0.9% Additional Medicare Tax on that $30,000 excess, adding $270 to the employee's Medicare withholding on top of the base 1.45% applied to the full $230,000. The filer reconciles the exact amount owed on Form 8959 when filing.
Frequently asked questions
At what income does the Additional Medicare Tax kick in?
Does my employer match the Additional Medicare Tax?
Why might I owe Additional Medicare Tax even if my employer didn't withhold it?
Related Terms
Medicare Tax
A 1.45% payroll tax on all wages with no income cap, matched by employers. High earners pay an Additional Medicare Tax of 0.9% on wages over $200,000 (single).
FICA
Federal Insurance Contributions Act taxes that fund Social Security (6.2%) and Medicare (1.45%). Both employees and employers pay FICA, totaling 15.3% on wages.
Net Investment Income Tax (NIIT)
A 3.8% surtax on investment income (interest, dividends, capital gains, rental income) for individuals with modified AGI above $200,000 (single) or $250,000 (married filing jointly).