Self-Employment Tax Calculator

This professional-grade calculator estimates your US federal self-employment (SE) tax, breaking out Social Security and Medicare, showing the deductible half, and optionally estimating the 0.9% Additional Medicare Tax. It is designed for freelancers, contractors, and small-business owners seeking fast, accurate planning insights.

Calculator

Filing status *
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Advanced coordination (optional)
If you also have W-2 income, enter it below. This ensures correct Social Security wage base coordination and Additional Medicare threshold checks.
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This tool reflects federal rules only (no state or local taxes). For planning purposes; not tax advice.

Results

Net earnings from SE (92.35% of net income)
$0.00
Social Security taxable SE earnings
$0.00
Social Security tax (12.4%)
$0.00
Medicare tax (2.9%)
$0.00
Self-employment tax (SS + Medicare)
$0.00
Deductible part of SE tax (50%)
$0.00
Estimated Additional Medicare Tax (0.9%)
$0.00

Tip: The deductible half does not include any Additional Medicare Tax.

Data Source and Methodology

Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti da questa fonte.

The Formula Explained

Mathematical formulas used to compute self-employment tax.

Let: N = net self-employment income; E = 0.9235 × max(0, N) Social Security wage base: W_b (year-dependent). W_2^{SS} = W-2 Social Security wages. S = min(E, max(0, W_b − min(W_2^{SS}, W_b))) T_{SS} = 0.124 × S T_{Med} = 0.029 × E T_{SE} = T_{SS} + T_{Med} Deduction = 0.5 × T_{SE} Additional Medicare (estimate): T_{AM} = 0.009 × max(0, (W_2^{Med} + E) − \text{Threshold(status)})

Glossary of Variables

Symbol / Field Definition
N — Net self-employment income Your annual net profit from self-employment (after expenses).
E — Net earnings for SE tax 92.35% of N, per IRS Schedule SE.
W_b — Social Security wage base Maximum earnings subject to Social Security in a given year.
W_2^{SS} Your W-2 Social Security wages (Box 3), used to reduce remaining wage base.
W_2^{Med} Your W-2 Medicare wages (Box 5), used for Additional Medicare Tax threshold testing.
S — SS taxable SE earnings The portion of E subject to 12.4% Social Security, coordinated with W-2 wages.
T_SS Social Security tax = 12.4% × S.
T_Med Medicare tax = 2.9% × E.
T_SE Total self-employment tax = T_SS + T_Med.
Deduction Above-the-line deduction equal to 50% of T_SE (excludes any Additional Medicare Tax).
T_AM Estimated Additional Medicare Tax = 0.9% of combined (W-2 Medicare + E) over filing-status threshold.

How It Works: A Step-by-Step Example

Scenario: Tax year 2024; Filing status: Single; Net SE income N = $120,000; W-2 Social Security wages = $40,000; W-2 Medicare wages = $40,000. Wage base W_b = $168,600.

  1. Compute E = 0.9235 × 120,000 = 110,820.
  2. Remaining SS headroom = W_b − W_2^{SS} = 168,600 − 40,000 = 128,600.
  3. SS taxable S = min(E, 128,600) = 110,820.
  4. T_SS = 12.4% × 110,820 = 13,741.68.
  5. T_Med = 2.9% × 110,820 = 3,213.78.
  6. T_SE = 13,741.68 + 3,213.78 = 16,955.46.
  7. Deduction = 50% × 16,955.46 = 8,477.73.
  8. Threshold (Single) = $200,000. Combined for addl Medicare = 40,000 + 110,820 = 150,820 ≤ 200,000 ⇒ T_AM = 0.

Result: SE tax ≈ $16,955.46; Deductible half ≈ $8,477.73; Estimated Additional Medicare Tax = $0.

Frequently Asked Questions (FAQ)

Do I apply the 92.35% factor even if I have a loss?

No. Losses don’t generate SE tax. The 92.35% factor applies to positive net income; if N ≤ 0, SE tax is zero.

Why do Social Security and Medicare use different rules?

Social Security has an annual wage base cap; Medicare has no cap. Both use net earnings (92.35% of net income) for self-employed individuals.

How does this tool handle multiple businesses?

Enter your combined net profit across all sole proprietorships. The wage base applies to total net earnings for the year.

Is the Additional Medicare Tax part of SE tax?

It is a separate surtax (0.9%) on wages and self-employment earnings above filing-status thresholds. It’s not included in the deductible half of SE tax.

Can this calculator estimate quarterly payments?

This page focuses on SE tax. For estimated tax payments, consult IRS Publication 505 and your full income picture (credits, deductions, withholding).

Does the calculator include state taxes?

No. It covers federal SE tax only. State and local obligations vary.

Where can I find my W-2 Social Security and Medicare wages?

Box 3 shows Social Security wages; Box 5 shows Medicare wages. Use Box 5 for Additional Medicare threshold checks.