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Salary & Taxes
Self-Employment Tax Calculator — SE Tax, Social Security & Medicare
The 15.3% SECA tax behind every freelance, gig and 1099 dollar — and the half you get back
Self-employment tax — formally SECA, the Self-Employment Contributions Act levy — is the one line on Schedule SE that trips up nearly every new freelancer, gig driver and side-hustler. It is not income tax. It is your Social Security and Medicare contribution, the exact equivalent of the FICA that gets withheld from a W-2 paycheck. The twist: a W-2 employer splits FICA with the worker, paying half and withholding half. When you work for yourself there is no employer to share the load, so you carry both halves yourself. That doubled-up contribution is what makes the combined SECA rate 15.3%, and this calculator isolates exactly that number — nothing more.
The arithmetic on Schedule SE has one quirk worth understanding. SECA is never charged on your raw Schedule C profit. You first knock it down to 92.35% of your net earnings — the 0.9235 multiplier mirrors the employer-side FICA a regular boss would have paid out of pre-tax money, so the playing field stays level. That trimmed figure is your SECA base, and the 15.3% splits into two named contributions:
SECA = (net earnings × 0.9235) × 15.3%, where 15.3% = 12.4% Social Security (OASDI) + 2.9% Medicare (HI).
Only the Social Security slice is capped: the 12.4% stops once your base clears the annual contribution ceiling, which the SSA indexes upward each year (it sits at $176,100 for the 2025 tax year). Every dollar past that ceiling is free of Social Security tax but still feeds the uncapped 2.9% Medicare piece.
Worked example. A $50,000 Schedule C profit shrinks to a $46,175 base (50,000 × 0.9235). Social Security runs 46,175 × 12.4% = $5,725.70; Medicare runs 46,175 × 2.9% = $1,339.08; together that is $7,064.78 of SECA. Crucially, you then claim half of it — $3,532.39 — as an above-the-line deduction on Form 1040. That deduction shrinks the income your income tax is figured on; it never reduces the SECA bill itself.
Which points to the one thing this tool deliberately leaves out: it does not compute your federal income tax. SECA stacks on top of the ordinary income tax you owe on the same profit, so to see your full freelance bill, run this estimate alongside our Federal Income Tax Calculator — the two read as a matched pair, one sizing your Social Security and Medicare, the other your bracket-based income tax. A practical habit is to park roughly 25–30% of every profit dollar for the combined hit and send quarterly estimated payments so April never ambushes you.
This is an informational SECA estimate only — it ignores the 0.9% Additional Medicare Tax on high earners, the QBI deduction, state tax and your income-tax brackets. Not tax advice; confirm with a CPA or the IRS.
📖 See also: Self-Employment Tax Explained for 1099 Workers
Calculator
Fill in the fields and click "Calculate" for instant results.
📰 Formula
• Taxable base = net self-employment income × 0.9235 • Social Security = min(base, $176,100) × 12.4% • Medicare = base × 2.9% (no cap) • Total SE tax = Social Security + Medicare • Deductible half = SE tax ÷ 2 (above-the-line deduction)
📰 Formula
• Taxable base = net self-employment income × 0.9235 • Social Security = min(base, $176,100) × 12.4% • Medicare = base × 2.9% (no cap) • Total SE tax = Social Security + Medicare • Deductible half = SE tax ÷ 2 (above-the-line deduction)
🧪 Worked examples
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Example 4
⚠️ Common mistakes
- Forgetting SE tax exists — it's on top of regular income tax, not instead of it.
- Applying 15.3% to your full profit instead of 92.35% of it.
- Capping Medicare like Social Security — Medicare (2.9%) has no income ceiling.
- Deducting the full SE tax instead of only half on the front of Form 1040.
💡 Tips
- Set aside about 25–30% of profit for SE plus income tax, and pay quarterly to avoid penalties.
- Only the Social Security portion halts at the yearly contribution ceiling — Medicare never stops.
- The deductible half lowers your income tax, not your self-employment tax.
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❓ Frequently asked questions
What is self-employment tax?
Self-employment tax is the Social Security and Medicare tax that self-employed people pay on their net business profit. Because you're both employer and employee, you owe both halves — a combined 15.3% (12.4% Social Security + 2.9% Medicare) on 92.35% of your net earnings.
How much is self-employment tax in 2025?
The headline SECA rate is 15.3%, split into 12.4% for Social Security and 2.9% for Medicare. It bites 92.35% of your net profit, not the whole amount. The Social Security half only runs until your base reaches the 2025 contribution ceiling; the Medicare half keeps applying with no ceiling at all.
Why is SE tax calculated on 92.35% of my income?
The 0.9235 factor (1 − 7.65%) approximates the employer-half deduction a regular employer would have made. It reduces your taxable base so self-employed people aren't taxed on the portion an employer would have effectively paid pre-tax.
How do I calculate self-employment tax on $50,000?
Multiply $50,000 by 0.9235 to get a $46,175 base, then by 15.3%. That's $7,064.78 in SE tax — $5,725.70 Social Security plus $1,339.08 Medicare. You can deduct half ($3,532.39) above the line on Form 1040.
Is self-employment tax the same as income tax?
No — they are two separate bills on the same profit. SECA funds Social Security and Medicare; income tax funds everything else and is figured on your tax brackets. This calculator handles only the SECA side, so pair it with our Federal Income Tax Calculator to see the income-tax layer and your true total liability as a freelancer.
Can I deduct part of my self-employment tax?
Yes. You deduct one-half of your SE tax as an above-the-line adjustment on Form 1040. That lowers your adjusted gross income and therefore your income tax — but it does not reduce the SE tax itself.
Do I owe self-employment tax on a small side hustle?
If your net self-employment earnings are $400 or more for the year, you generally owe SE tax and must file Schedule SE — even if it's a part-time side gig. Below $400, you typically don't owe SE tax on that income.
What is the Social Security contribution ceiling and how does it cap my tax?
It is the annual earnings limit the SSA raises most years; for the 2025 tax year it lands at $176,100. The 12.4% Social Security portion of SECA stops once your 92.35% base reaches that line, so very high earners save 12.4% on each dollar above it. The 2.9% Medicare portion has no such ceiling and keeps charging every dollar.
How do I pay self-employment tax?
You report it on Schedule SE and pay it with your annual Form 1040. Most self-employed people also make quarterly estimated tax payments (April, June, September, January) to cover SE tax plus income tax and avoid an underpayment penalty.