Medicare Additional 0.9% Tax 2027 Calculator
Estimate the 0.9% Additional Medicare Tax owed on wages, SE income, and RRTA compensation for 2027 (Form 8959).
What Is the Additional Medicare Tax?
The 0.9% Additional Medicare Tax applies to W-2 wages, RRTA compensation, and self-employment earnings above $200,000 single / $250,000 MFJ / $125,000 MFS. Enacted under the Affordable Care Act in 2013, the thresholds are NOT indexed for inflation — meaning more taxpayers hit them every year. For 2027, the thresholds remain unchanged. Source: IRC §3101(b)(2), Form 8959. Last updated: May 2026.
How Employer Withholding Works
Employers must withhold the extra 0.9% on wages OVER $200,000 paid to any single employee — regardless of filing status or other income. This creates two common situations: (1) MFJ couples each earning under $200K but jointly over $250K owe additional tax not withheld, (2) MFS filers face mandatory withholding only above $200K but their threshold is $125K, so they owe more.
Self-Employment Income Treatment
Self-employed individuals reduce SE earnings by 7.65% (employer-equivalent FICA) before applying the threshold test. The 0.9% applies to net SE earnings × 92.35% that exceeds the filing-status threshold (after subtracting W-2 wages). Pay via quarterly estimated taxes — no payroll withholding catches it.
Interaction with NIIT
Both the 0.9% Additional Medicare Tax (on earned income) AND the 3.8% NIIT (on investment income) can hit the same taxpayer in the same year. They have similar but separate thresholds. High earners with mixed income should run both calculations — combined burden can be 4.7%+ on the marginal dollar.