Self-Employment Tax Calculator
Your numbers
The 15.3% every freelancer hears about — computed the way Schedule SE actually works, including the wage-base cap most quick estimates miss.
Revenue minus business expenses — your Schedule C bottom line
How we calculate this
Self-employment tax is both halves of Social Security and Medicare — the 7.65% your old employer paid plus the 7.65% you paid, now all yours. But the headline 15.3% is applied to 92.35% of your net profit, not all of it. That multiplier exists to mirror W-2 life: employees don't pay payroll tax on their employer's half, so Schedule SE first removes the equivalent share. Multiplying 15.3% straight against profit — the mistake most quick estimates make — overstates the tax by hundreds of dollars.
The wage base is the second thing quick estimates miss. The 12.4% Social Security piece stops at $184,500 of 2026 earnings (the SSA taxable maximum) — and W-2 wages consume that base first. If your day job pays $150,000, only $34,500 of your side income's SE earnings pays Social Security tax, no matter how big the side income is. The 2.9% Medicare piece has no cap and applies to every dollar of SE earnings.
Additional Medicare Tax is a separate thing. Above $200,000 of combined earnings ($250,000 joint, $125,000 married filing separately), a 0.9% surtax kicks in per IRC §3101(b)(2). We show the slice attributable to your self-employment income as its own line because that's how Form 8959 computes it — it is not part of SE tax, and it does not count toward the ½ deduction. Your employer separately withholds this surtax on W-2 wages over $200,000.
Half of it comes back. The employer-half equivalent of your SE tax is an above-the-line deduction on Schedule 1 — it reduces the income you pay income tax on, no itemizing required. It does not reduce the SE tax itself. And if 92.35% of your profit lands under $400, Schedule SE doesn't apply at all — we tell you so instead of showing a silent zero.
What this page deliberately isn't: your income tax. SE tax is the payroll piece only. What you actually send the IRS each quarter — income tax, safe harbor, withholding credits — is the quarterly estimated tax calculator's job, and the two tools share the same Schedule SE math underneath.
Real scenarios
Full-time freelancer, $80k profit: $11,303.64 — not $12,240
The naive 15.3% × $80,000 estimate says $12,240. Schedule SE says $11,303.64, because the tax applies to $73,880 of SE earnings after the 92.35% multiplier — about 14.1% of profit, not 15.3%. And $5,651.82 of it comes back as a deduction against income tax at filing. Budget the real number, not the scary one.
$150k day job + $60k side income: the wage base does the work
The job's wages already used $150,000 of the $184,500 Social Security base, so only $34,500 of the side gig's $55,410 in SE earnings pays the 12.4% — $4,278 instead of $6,871. Total SE tax: $5,884.89, plus $48.69 of Additional Medicare because combined earnings crossed $200,000. A flat 15.3%-style estimate would have called it $8,477 — roughly $2,600 too high.
High earner, $220k profit: Social Security tops out
At $203,170 of SE earnings, the 12.4% piece caps at the full wage base: $22,878 — the most anyone pays into Social Security through SE tax in 2026 (Medicare, uncapped, keeps going). Total: $28,769.93 plus $28.53 of Additional Medicare. Past the cap, each extra dollar of profit faces only 2.9% + 0.9% — the marginal payroll rate falls just as income rises.