Self-Employment Tax Calculator — See Your Exact Social Security and Medicare Bill

Self-employment tax is the 15.3% combined Social Security and Medicare tax that freelancers and contractors pay instead of the split employer/employee payroll tax a traditional employee has withheld. TidyPapers' Self-Employment Tax Calculator, at tidypapers.com/self-employment-tax-calculator/, works out the exact figure from your profit — this guide covers every input and every line of the result.

This tool is US-specific (Social Security/Medicare/Schedule SE are US tax concepts) and uses 2026 tax year figures, with the calculator's own disclaimer stated on the page: "2026 tax year figures (Social Security wage base $184,500). Estimates only, not tax advice." Also stated directly: "Your figures aren't saved or sent anywhere. Everything is calculated in your browser."

Step 1 — Enter your net profit

Net self-employment profit (USD) — a number field, pre-filled with an example value of 100000. The page's own hint: "Your Schedule C net profit for the year, before self-employment tax." This is your income after business expenses, not your gross revenue — if you're not sure of this number, it's the "net profit" line from your Schedule C tax form (US filers) or your income-minus-expenses total for the year.

Step 2 — Enter W-2 wages, if any (optional)

W-2 wages already earned this year (optional) — a number field for income you've already earned as a regular employee this year, if you also have a day job or part-time employment alongside freelancing. This matters because Social Security tax has an annual cap shared across all your earnings (see below), so declaring W-2 wages here gives a more accurate result if you're close to that cap.

Step 3 — Calculate

Click "🧮 Calculate my SE tax →". The result appears immediately (no page reload), broken down into every line below.

Reading the result

1. Net earnings from self-employment (92.35% of profit) — your profit multiplied by 92.35%. This adjustment mirrors the fact that employees don't pay Social Security/Medicare tax on the half their employer contributes — self-employed people get an equivalent discount before the tax applies.
2. Social Security portion (12.4%) — 12.4% of your net earnings, but only up to the annual Social Security wage base, $184,500 for 2026. Net earnings above that cap owe no further Social Security tax.
3. Medicare portion (2.9%) — 2.9% of your net earnings, with no cap — it applies to all of it.
4. Additional Medicare (0.9% above $200,000) — an extra 0.9% Medicare tax on net earnings above $200,000. This is $0 for anyone under that threshold.
5. Total self-employment tax — the sum of the three tax lines above; this is the actual dollar figure to set aside for self-employment tax alone (not counting regular income tax).
6. Deductible half of SE tax (income tax deduction) — half of your total SE tax can be deducted from your income before calculating regular income tax; this line shows that deductible amount so you (or your accountant) can use it elsewhere.
7. Effective SE tax rate — your total self-employment tax as a percentage of your original profit figure (typically a bit under 15.3%, since the 92.35% adjustment and the Social Security cap both pull it down slightly).

Worked example printed on the page: on $100,000 net profit with no W-2 wages — net earnings $92,350, Social Security $11,451.40, Medicare $2,678.15, additional Medicare $0 (under the $200,000 threshold), total self-employment tax $14,129.55, an effective rate of about 14.13%.

What this number doesn't include

This calculator only covers self-employment tax (Social Security + Medicare). It does not include regular federal income tax, state income tax, or any other withholding. For the fuller picture of what to actually set aside each month — including income tax and a state estimate — use How Much to Set Aside for Taxes, which the page links to directly and which reuses this same self-employment tax math as part of a larger total.

Where this connects to other tools

This calculator does not save your figures and doesn't connect automatically to any other TidyPapers tool — you'd carry the total self-employment tax figure over manually if you want to log it as a component in the Freelancer Tax Dashboard. It cross-links to the Tax Dashboard, Payment Fees Comparison, and the Late Payment Interest Calculator.