Base Medicare tax
1.45 percent on all wages. No wage base cap. Your employer matches 1.45 percent on the employer side. Total per-worker cost is 2.9 percent.
Additional Medicare Tax
0.9 percent on wages above $200,000 single or $250,000 married filing jointly. Employee-only, no employer match. Employers withhold the Additional Medicare once your wages with that employer exceed $200,000 in a calendar year, regardless of filing status. If you have multiple jobs and total wages exceed the threshold, you may owe more (or less) at filing time.
What it funds
Medicare Part A (hospital insurance) for people 65+, certain disabled workers, and end-stage renal disease patients. Medicare Parts B and D are funded primarily through premiums, not the payroll tax.
What does and does not reduce Medicare wages
Section 125 cafeteria plan deductions (pre-tax health insurance, FSA via payroll, HSA via payroll under cafeteria plan) reduce Medicare wages.
Pre-tax 401(k) contributions do NOT reduce Medicare wages.
Self-employment
1099 contractors pay 2.9 percent self-employment Medicare on all net earnings (no cap). Plus 0.9 percent above the thresholds. Half of the 2.9 percent is deductible above the line.
How it shows on your stub
MED, MEDICARE, FED MED, FICA-MED. The Additional Medicare Tax appears as a separate line if applicable.