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Additional Medicare Tax Calculator

Estimate Additional Medicare Tax under Form 8959 from annual Medicare wages, self-employment income, RRTA compensation, filing status, and withholding records. Use it to review the separate wage, self-employment, and railroad compensation calculations before preparing a federal return.

Inputs

Form 8959 inputs

The 2026 Form 8959 instructions are draft as of October 27, 2026. Confirm the final form instructions before filing a 2026 return.

For married filing jointly, enter combined amounts for both spouses where the field refers to a return total. Otherwise, enter the taxpayer's amounts.

Range: 0–100,000,000 $

Enter the return total for Form 8959 line 4: W-2 Box 5 Medicare wages plus applicable Form 4137 line 6 and Form 8919 line 6 amounts. For a joint return, combine both spouses.

Range: 0–100,000,000 $

Enter the combined Schedule SE line 6 amount for the return. Enter 0 when there is no positive self-employment amount subject to this calculation.

Range: 0–100,000,000 $

Enter railroad retirement compensation and tips for Form 8959 Part III, using the amount from the applicable railroad wage statements. For a joint return, combine both spouses.

Range: 0–100,000,000 $

Enter total Medicare tax withheld shown in W-2 Box 6 for the return. The calculator estimates the Additional Medicare Tax portion by subtracting 1.45% of Form 8959 Medicare wages, floored at zero.

Range: 0–100,000,000 $

Enter Additional Medicare Tax withheld on RRTA compensation from the applicable W-2 Box 14 or Form CT-2 records. For a joint return, enter the return total.

Result

Tax after withholding credit (negative may indicate excess withholding)
180.00
Estimated total Additional Medicare Tax
180.00
Calculation details
Additional Medicare Tax withheld on wages
0.00
Estimated regular Medicare withholding at 1.45%
1,885.00
Threshold remaining for self-employment income
120,000.00
Additional tax on RRTA compensation
0.00
Additional tax on self-employment income
180.00
Additional tax on wages
0.00
RRTA compensation above threshold
0.00
Self-employment income above remaining threshold
20,000.00
Wages above threshold
0.00
Filing-status threshold
250,000.00
Total Additional Medicare withholding credit
0.00
Tax-year basis
Uses the final 2025 Instructions for Form 8959.
How to interpret this result
Total Additional Medicare Tax is shown separately for Medicare wages, self-employment income, and RRTA compensation. Tax after withholding is this estimate minus the Additional Medicare Tax withholding credit; it is not the balance due or refund for the full federal return.
Applicability and limits
This estimates federal Additional Medicare Tax for the selected tax year and filing status. It does not calculate regular Medicare or Social Security tax, self-employment tax, the full Form 1040 result, state tax, or employer payroll withholding. The employer's $200,000 per-employer withholding trigger is separate from the filing-status thresholds used for tax liability.
Calculation basis
Uses the 0.9% Additional Medicare Tax rate and Form 8959 threshold rules: $200,000 for Single, Head of household, or Qualifying surviving spouse; $250,000 for Married filing jointly; and $125,000 for Married filing separately. Wages reduce the threshold available against self-employment income. RRTA compensation is calculated separately. W-2 Box 6 withholding credit is estimated as Box 6 minus 1.45% of Form 8959 Medicare wages, floored at zero, then combined with the supplied RRTA Additional Medicare Tax withholding.

Formula

Calculation logic

Formula definitions and substituted values.

What to check

  • An employee enters one pay period, the relevant payroll rates, and current deductions to estimate take-home pay or withholding.
  • Use it before a payroll change, bonus payment, or W-4 update.
  • This estimates federal Additional Medicare Tax for the selected tax year and filing status. It does not calculate regular Medicare or Social Security tax, self-employment tax, the full Form 1040 result, state tax, or employer payroll withholding. The employer's $200,000 per-employer withholding trigger is separate from the filing-status thresholds used for tax liability.

Related calculators

This estimates federal Additional Medicare Tax for the selected tax year and filing status. It does not calculate regular Medicare or Social Security tax, self-employment tax, the full Form 1040 result, state tax, or employer payroll withholding. The employer's $200,000 per-employer withholding trigger is separate from the filing-status thresholds used for tax liability.