Self-employment tax calculator

How the formula works

A W-2 employee and their employer split FICA down the middle: 6.2% each for Social Security, 1.45% each for Medicare. When you work for yourself you are both parties, so you owe both halves — a combined 15.3%. That is what self-employment (SECA) tax is: the employer and employee shares of Social Security and Medicare, rolled into one.

It is not charged on your whole profit. Because an employer's share of FICA is itself a business expense, the law lets you shave off an equivalent slice first — you pay SE tax on net earnings from self-employment, which is 92.35% of profit:

The 0.9235 is exactly \(1 - 0.0765\), and 0.0765 is 7.65% — half of the 15.3% rate. Removing it puts a self-employed person on the same footing as an employee, whose taxable wages already exclude the employer's contribution.

Social Security applies only up to an annual wage cap, and that cap is shared with any W-2 wages you have already had taxed this year:

Medicare has no cap: 2.9% applies to every dollar of net earnings, and a further 0.9% Additional Medicare surtax lands on earnings above $200,000 (single) or $250,000 (married filing jointly). The three pieces add up to the SE tax.

Finally, half of the Social Security-plus-regular-Medicare amount — the employer-equivalent share — comes back as an above-the-line deduction against your income tax (not against the SE tax itself):

The 0.9% surtax is excluded from that half — it is never deductible.

The figures here are for tax year 2026 and change annually: the Social Security wage base is $184,500, the combined rates are 12.4% Social Security and 2.9% Medicare (15.3% together), and the Additional Medicare threshold is $200,000 single / $250,000 married filing jointly.

What each input means

Net self-employment profit

Your business profit after expenses — the bottom line of a Schedule C, or your share of a partnership's earnings. Deducting business expenses is what happens before this number; the calculator takes profit as already net, so do not subtract expenses again here.

Filing status

Single or married filing jointly. It matters only for the 0.9% Additional Medicare surtax, whose threshold is $200,000 single and $250,000 jointly. The 15.3% base rate and the Social Security cap do not depend on filing status.

Other W-2 wages this year

Wages from a regular job that have already been subject to Social Security this year. Social Security has one shared annual cap across all your earnings, so W-2 wages use up part of it — if they already fill the $184,500 base, your self-employment income owes no more Social Security, only Medicare. Leave it at 0 if self-employment is your only income.

A worked example

The worksheet's defaults: $80,000 of net profit, single, with no other W-2 wages.

• Net earnings from self-employment: $80,000 × 0.9235 = $73,880. This — not the full $80,000 — is the base for everything below.
• Social Security: the cap is $184,500 and no W-2 wages have used any of it, so all $73,880 is inside the cap: $73,880 × 12.4% = $9,161.
• Medicare: $73,880 × 2.9% = $2,143. Net earnings are below $200,000, so there is no 0.9% surtax.
• Total self-employment tax: $9,161 + $2,143 = $11,304 — about 14.1% of the original $80,000 profit, which is 15.3% of the 92.35% base.
• Deductible half: ($9,161 + $2,143) ÷ 2 = $5,652, taken above the line against your income tax.
• Estimated quarterly payment: $11,304 ÷ 4 = $2,826 — but read the note below: this covers the SE tax only, not your income tax.

The quarterly figure is not your whole estimated payment. A real quarterly estimate also includes federal (and usually state) income tax on the same profit, minus the deductible half above. This tool sizes the SE tax piece; for the income-tax piece, run the profit through the take-home pay calculator and add the two.

Assumptions and limits

• The figures are for tax year 2026 — the Social Security wage base and the surtax thresholds are adjusted over time, so this page's results drift out of date unless the constants are updated.
• Profit is taken as already net of business expenses. If you have not yet subtracted expenses, do that first; entering gross revenue overstates the tax.
• This is self-employment tax only. It ignores the income tax on the same profit, the qualified business income (QBI) deduction, and any credits — so it is one part of your total bill, not the whole. Link to the take-home tool above for the income-tax side.
• The 0.9% Additional Medicare figure is an approximation of the actual Form 8959 calculation, which combines W-2 wages and SE income on a single worksheet with the withholding your employer already took. Near the threshold the exact number can differ.
• This is arithmetic, not advice. It shows what the inputs imply under one year's rules; it cannot see your whole tax situation.

Questions people ask

What is self-employment tax and why is it 15.3%?

It is Social Security and Medicare tax for people who work for themselves. An employee pays 6.2% + 1.45% = 7.65% and the employer matches it; a self-employed person is both, so they owe the full 12.4% + 2.9% = 15.3%. It is separate from — and on top of — the income tax you also owe on the same profit.

What is the 92.35% factor?

Self-employment tax is charged on net earnings, which are 92.35% of your profit, not the whole thing. The 0.9235 is \(1 - 0.0765\), and 0.0765 is the employer's 7.65% share of FICA. Removing it mirrors how an employee's taxable wages already exclude what the employer contributes, so the two are taxed on comparable bases.

Is any of it deductible?

Half of it is — the employer-equivalent share of Social Security plus regular Medicare. On the default scenario that is $5,652, taken as an above-the-line deduction that reduces your income tax (it does not reduce the SE tax itself). The 0.9% Additional Medicare surtax is the one piece that is never deductible.

Do I really have to pay quarterly?

Usually yes. With no employer withholding, the IRS expects estimated payments four times a year — for 2026 income they fall on April 15, June 15, September 15, 2026, and January 15, 2027. The safe harbor is to pay at least 90% of this year's total tax or 100% of last year's (110% if your income is high), which avoids an underpayment penalty. Remember the quarterly figure here is the SE-tax slice only; your actual payment must also cover the income tax on the same profit.

How does electing S-corp status change this?

An S-corporation splits your profit into a reasonable salary — which runs through payroll and is fully hit by Social Security and Medicare — and distributions, which are not subject to SE or payroll tax. Only the salary is taxed, so on the default $80,000 profit, paying yourself a $60,000 salary would cut the tax to roughly $8,478, about $2,826 less. The catch is real: the salary must be defensible for your work, and the S-corp adds payroll filings, a separate return and administrative cost. It is a common move above a certain profit level, but only worth it once the savings clear those costs.