W-2 Box 6 — Medicare tax withheld
1.45% of Box 5, plus 0.9% Additional Medicare Tax on the portion of Box 5 above $200,000 at any single employer.
At a glance — Box 6
- Box name
- Medicare tax withheld
- Reports to
- Feeds Form 8959 (Additional Medicare Tax); not on 1040 directly.
- Check against
- Box 5 × 1.45%, plus 0.9% × (Box 5 − $200,000) if Box 5 > $200,000.
What Box 6 means
Box 6 reports Medicare tax withheld. For wages up to $200,000, the rate is 1.45%. For wages above $200,000 at a single employer, your employer must withhold an additional 0.9% (Additional Medicare Tax) — so the marginal rate above $200k is 2.35% from your paycheck. Your employer's matching 1.45% does not appear on your W-2.
Your actual Additional Medicare Tax liability is computed on Form 8959 using your filing-status threshold ($200,000 single, $250,000 MFJ, $125,000 MFS). Multiple-employer scenarios often produce over- or under-withholding of the 0.9%.
Tax return implications
- Goes on Form 8959 to reconcile Additional Medicare Tax against your filing status threshold.
- Over-withholding (e.g., one employer paid over $200k but your MFJ threshold is $250k) produces a credit on your 1040.
- Under-withholding (e.g., two employers each under $200k, combined above $250k MFJ) means you owe extra on Form 8959.
Common pitfalls & things to check
- Don't confuse Box 6 with the 3.8% Net Investment Income Tax (NIIT) — that's on Form 8960 and applies to investment income, not wages.
- Box 6 can look high relative to Box 2 (federal income tax) because Medicare has no deductions — it's computed on gross Medicare wages.
Related W-2 boxes
Box 5 — Medicare wages and tips
Your wages subject to Medicare tax. Unlike Social Security, there is no wage base cap — Box 5 can exceed Box 3 on high salaries.
Box 1 — Wages, tips, other compensation
Your taxable federal wages for the year — gross pay minus pre-tax deductions like traditional 401(k), Section 125 cafeteria plan contributions, and pre-tax HSA.
Box 2 — Federal income tax withheld
Total federal income tax your employer withheld from your paychecks during the year, based on your Form W-4 elections.
Box 3 — Social security wages
Your wages subject to Social Security tax, capped at the annual wage base. Differs from Box 1 because traditional 401(k) deferrals are not excluded.
Reconciling your W-2 at tax time? Use the paycheck calculator to verify expected federal, Social Security, and Medicare withholdings on your salary, and the federal income tax calculator to estimate your refund or balance owing before you file.
Sources
W-2 box definitions per IRS General Instructions for Forms W-2 and W-3 and IRC §6051. Rates and thresholds current for tax year 2025 (file by April 15, 2026); 2026 figures included where published.