Additional Medicare Tax Calculator 2026 (Form 8959)

Calculate the 0.9% Additional Medicare Tax under IRC § 3101(b)(2) and Form 8959 for 2026. Combine W-2 Medicare wages, self-employment earnings, and RRTA compensation, subtract the filing-status threshold ($200k single, $250k MFJ, $125k MFS), and see the tax plus any additional amount owed beyond what your employer withheld. Free, private, runs entirely in your browser.

Filing Status
Threshold per IRC § 3101(b)(2). MFS spouses share the lowest threshold ($125k each).
Income (Form 8959 Inputs)
Sum of Box 5 across all W-2s for the taxpayer. Box 5 (Medicare wages) is NOT capped — unlike Box 3 (SS wages).
Add only if filing jointly. Couples often owe additional tax because employer withholds only on >$200k per individual job.
Net SE earnings × 92.35% (the SE multiplier already applied).
Tier 1 RRTA Medicare-equivalent comp. Most taxpayers leave this at 0.
Withholding (Form 8959 Part IV)
Employer withholds 0.9% only on wages above $200k from THAT employer. Couples + multi-job earners often see under-withholding here.
From your CT-2 / W-2 if applicable. Most non-railroad taxpayers leave at 0.
Additional Medicare Tax (total)
$0
Excess over threshold
$0
Already withheld
$0
Extra owed at filing
$0
Form 8959 Line Amount
2026 Form 8959 thresholds: Single / HoH / QW $200,000 · MFJ $250,000 · MFS $125,000. The 0.9% Additional Medicare Tax applies to the lesser of (Medicare wages + SE income + RRTA) over the threshold — there is NO inflation adjustment, so these figures are unchanged since 2013.

Source: IRS Form 8959 + IRC § 3101(b)(2). Last updated: May 3, 2026.
Ad Space

What Is the Additional Medicare Tax?

The Additional Medicare Tax is an extra 0.9% Medicare tax imposed by IRC § 3101(b)(2) on Medicare wages, self-employment earnings, and RRTA compensation that exceed a filing-status threshold. It was added by the Affordable Care Act in 2013 and is reported by individuals on IRS Form 8959. Unlike the regular 1.45% Medicare tax that applies from the first dollar, the additional 0.9% only applies to the portion above $200,000 (single, HoH, QW), $250,000 (married filing jointly), or $125,000 (married filing separately). Source: IRS Form 8959 instructions. Last updated: May 3, 2026.

The thresholds have NOT been indexed for inflation since enactment, so each year more middle-to-upper-income workers cross them. The tax is paid only by the employee — there is no employer-matching portion. Self-employed individuals pay it through the SE tax computation on Schedule SE and report it on Form 8959.

Why Couples Often Owe Additional Medicare Tax

An employer is required to withhold the 0.9% only after a single employee\'s wages with that employer exceed $200,000 — regardless of filing status. So a married couple where each spouse earns $180,000 would have NO Additional Medicare Tax withheld during the year (each is under the $200k single-job threshold), but their joint Medicare wages of $360,000 are $110,000 above the MFJ threshold of $250,000. They owe 0.9% × $110,000 = $990 at filing. This is a frequent under-withholding surprise — the only fix is voluntary additional withholding via a Form W-4 adjustment or quarterly estimated tax payments.

Form 8959 Line-by-Line

Form 8959 has four parts. Part I calculates the tax on Medicare wages: line 1 sums all W-2 Box 5 amounts, line 7 subtracts the filing-status threshold, and line 7 × 0.9% on line 7 yields the wage-based tax. Part II handles self-employment income similarly but the threshold is reduced by Medicare wages already counted (no double-threshold). Part III computes RRTA railroad compensation. Part IV reconciles withholding: the employer\'s 0.9% withholding (W-2 Box 14, code AddlMedTax) is compared against the total tax computed in Parts I-III, and the difference is the extra amount owed (or refunded) at filing. The total flows to Schedule 2 of Form 1040, line 11.

How to Avoid an Underpayment Surprise

Three planning moves help. First, if you and your spouse are both employed and your combined wages exceed $250,000, request additional withholding by entering a flat extra dollar amount on Form W-4 line 4(c) — calculate the expected Additional Medicare Tax and divide by remaining pay periods. Second, self-employed earners with high SE income should add the projected 0.9% to their quarterly estimated tax payments (Form 1040-ES) to avoid an underpayment penalty. Third, if you have multiple jobs and any single employer pays you above $200,000, that employer will start withholding 0.9% from the first dollar above $200k — so the more your income concentrates with one employer, the less under-withholding risk you have. Source: IRS Form 8959 instructions, irs.gov. Last updated: May 3, 2026.