Self-Employment Tax (Schedule SE)
92.35% net-earnings adjustment, Social Security cap, Additional Medicare 0.9%, deductible half.
Example
You enter
- Net SE earnings (USD) 80000
- Tax year 2025
- Filing status single
You get
- Net earnings adjusted 73880
- Ss taxable 73880
- Social Security portion $9161.12
- Medicare portion $2142.52
- Total SE tax $11303.6
- Deductible half $5651.82
Checked against published worked examples from: IRS Schedule SE (Form 1040).
Details, formula, and sources
Formula or tableNet adjusted = net_se * 0.9235. SS tax = min(net_adjusted, ss_wage_base - w2_ss) * 0.124. Medicare = net_adjusted * 0.029. Additional Medicare = max(0, net_adjusted - max(0, threshold - w2_medicare_wages)) * 0.009 (Form 8959 Part II, lines 8-13). SE tax = sum. Deductible half = (SS + Medicare) / 2.
Source and editionSchedule SE (Form 1040). Social Security wage base from SSA annual wage-base announcement; Additional Medicare 0.9% threshold from IRC 3101(b)(2).
Free accessFree at irs.gov/forms-pubs/about-schedule-se-form-1040; SSA wage base at ssa.gov/oact/cola/cbb.html.
What governsEstimate only. Tax law changes. Confirm with the current IRS publication or a licensed CPA before filing.
API field namesnet_se_earnings, tax_year, filing_status, net_earnings_adjusted, ss_taxable, ss_tax, medicare_tax, se_tax, deductible_half
- Net-earnings adjustment 92.35%Schedule SE line 4a
- SS / Medicare rates 12.4% / 2.9% / 0.9% AdditionalIRC 1401 / 3101(b)(2)
- $400 filing threshold below this, no SE tax owedSchedule SE Part I
- Additional Medicare threshold reduced by W-2 Medicare wages (box 5); blank uses the SS wagesForm 8959 lines 9-11