Blog · 6 November 2026 · Tax year 2026
Self-employed estimated tax: how the 15.3% self-employment tax works
A W-2 employee never sees the full cost of Social Security and Medicare: the employer pays half (7.65%) and the employee pays half (7.65%), and both halves are withheld before the paycheck arrives. A self-employed person has no employer — so they pay both halves themselves, as self-employment tax, on top of ordinary federal income tax. That is why a freelancer's quarterly bill looks so much bigger than an employee's withholding on the same income, and why the familiar advice to “set aside 25–30%” is only roughly right. This post works through the actual 2026 calculation, step by step, with three worked examples from this site's calculator.
The 15.3%: two taxes, one rate
Self-employment tax is 15.3% of your net earnings from self-employment, made of two parts:
- 12.4% Social Security — on net earnings up to the 2026 Social Security wage base of $184,500. Earnings above that are exempt from the Social Security part.
- 2.9% Medicare — on all net earnings, with no cap. On top of that, the 0.9% Additional Medicare Tax applies to net earnings (plus wages, if any) above $200,000 for a single filer or $250,000 for married filing jointly.
Three details trip people up. First, the tax applies to net profit — what is left on Schedule C after business expenses — not to gross 1099 income. A freelancer who invoices $90,000 and spends $10,000 on the business pays self-employment tax on $80,000, not $90,000. Second, it applies to only 92.35% of that net profit. The 7.65% haircut exists because the employer's half of FICA is not itself taxed — the IRS treats the self-employed person as if they were their own employer and excludes the employer-share equivalent from the base. Third, there is a $400 floor: if your net earnings from self-employment are under $400 for the year, no self-employment tax is due at all (income tax may still be due — see do I need to pay quarterly taxes).
The five-step calculation
For a single filer with only 1099 profit, no W-2 wages and no credits, tax year 2026, the calculation runs like this. (The full assumptions — standard deduction, simplified 20% QBI, no state tax — are on the About page; the quarterly estimated tax calculator runs the same steps.)
- Net earnings: net profit × 92.35%.
- Self-employment tax: 12.4% of net earnings up to $184,500, plus 2.9% of all net earnings, plus 0.9% Additional Medicare above the threshold if it applies.
- Deduct half of it: one-half of the self-employment tax is an above-the-line deduction — it lowers your adjusted gross income (AGI) before income tax is figured. It is a deduction, not a credit: it saves income tax at your marginal rate, it does not reduce the self-employment tax itself.
- Income tax: AGI minus the 2026 standard deduction ($16,100 single), minus the simplified 20% QBI deduction, then the 2026 federal brackets (10% to 37%).
- Total and quarterly: self-employment tax + income tax, divided by four for the quarterly payment.
Worked example: $40,000 of 1099 profit
Single filer, $40,000 net profit, tax year 2026:
| Step | Calculation | Result |
|---|---|---|
| Net earnings | $40,000 × 92.35% | $36,940.00 |
| Social Security | 12.4% × $36,940.00 | $4,580.56 |
| Medicare | 2.9% × $36,940.00 | $1,071.26 |
| Self-employment tax | $4,580.56 + $1,071.26 | $5,651.82 |
| Deduct half of SE tax | $5,651.82 ÷ 2 | $2,825.91 |
| AGI | $40,000 − $2,825.91 | $37,174.09 |
| QBI deduction | 20% of $21,074.09 (capped) | $4,214.82 |
| Taxable income | $37,174.09 − $16,100 − $4,214.82 | $16,859.27 |
| Federal income tax | 10% × $12,400 + 12% × $4,459.27 | $1,775.11 |
| Total federal tax | $5,651.82 + $1,775.11 | $7,426.93 |
Four quarterly payments of $1,856.73. Notice the split: at this income the self-employment tax ($5,651.82) is more than three times the income tax ($1,775.11). That is normal at lower profits — the 15.3% starts from the first dollar of net earnings, while income tax only starts after the standard deduction and QBI have been taken off.
How the bill grows: $40,000, $100,000 and $200,000
Same assumptions — single filer, 1099 profit only, tax year 2026, simplified QBI:
| Net profit | Self-employment tax | Federal income tax | Total tax | Effective rate | Per quarter |
|---|---|---|---|---|---|
| $40,000 | $5,651.82 | $1,775.11 | $7,426.93 | 18.6% | $1,856.73 |
| $100,000 | $14,129.55 | $8,235.00 | $22,364.55 | 22.4% | $5,591.14 |
| $200,000 | $28,234.30 | $25,196.31 | $53,430.61 | 26.7% | $13,357.65 |
The $200,000 row shows the Social Security cap in action: net earnings are $184,700, but the 12.4% part stops at the $184,500 wage base, so Social Security tax is exactly $22,878.00 and only Medicare ($5,356.30) keeps growing. Additional Medicare is still $0 here, because net earnings of $184,700 sit below the $200,000 single threshold — a single filer crosses into the extra 0.9% only when wages plus net earnings pass $200,000. Check the $100,000 row against the homepage: the same $22,364.55 total and $5,591.14 quarterly figure appears there, from the same engine.
Why the 25–30% rule of thumb misleads
You will see “set aside 25–30% of every payment” everywhere, and it is not bad advice as a safety margin — but as an estimate it is wrong in both directions. At $40,000 of profit the real federal rate is 18.6%, so setting aside 30% locks up about $4,500 a year you did not need to reserve. At $200,000 the real rate is 26.7% before any state tax, so 25% leaves you short. The rate rises with income because income tax is progressive while self-employment tax is mostly flat — the only thing that flattens it is the Social Security cap, and that only bites above $184,500 of net earnings. Run your own number on the quarterly estimated tax calculator instead of a flat percentage, and re-run it whenever a big contract lands: how much you should pay in quarterly taxes walks through the same formula from the payment side.
If you also have a W-2 job
Mixing a salary with freelance income changes the Social Security part: your W-2 wages use up the $184,500 wage base first, so less of your net earnings is subject to the 12.4% piece. If your wages already pass $184,500, your freelance income pays only the 2.9% Medicare part (plus Additional Medicare if your combined income crosses the threshold). Your employer's withholding also counts toward the total: the quarterly payment is the total tax minus what was already withheld, and withholding is treated as paid evenly across the year even if it was not. The first post in this series works a $60,000 side-income example on top of an $80,000 salary. And if your income arrives unevenly through the year, the annualized income installment method can match each payment to the income actually earned by then instead of demanding four equal instalments.
What to do with the number
- Pay it quarterly, on the IRS dates. For tax year 2026 the due dates are 15 April, 15 June and 15 September 2026, and 15 January 2027 — see the full due-date guide. Paying the full annual amount once does not cure a late quarter: the penalty is figured quarter by quarter (see how the underpayment penalty is calculated).
- Consider the safe harbor instead. If last year's total tax was low, four equal payments of 100% of last year's tax (110% if last year's AGI was over $150,000) may be less than 90% of this year's tax and need no quarterly re-estimating — see the safe-harbor rule.
- Use a free payment channel. IRS Direct Pay and EFTPS cost nothing; card payments carry a processor fee. The practical steps and the three tagging mistakes that send a payment to the wrong year are in how to pay estimated taxes online.
- Keep the Schedule C records that make the number defensible. The 92.35% factor, the $400 floor and the half-SE-tax deduction all depend on net profit, and net profit depends on expenses you can prove. Track them monthly, not in January.
Bottom line
Self-employed estimated tax is two taxes wearing one quarterly payment: 15.3% self-employment tax on 92.35% of net profit — Social Security up to $184,500, Medicare on everything, plus 0.9% Additional Medicare above $200,000 single / $250,000 joint — and then federal income tax on what is left after half the SE tax, the standard deduction and QBI come off. At $40,000 of profit that is $7,426.93 a year, $1,856.73 a quarter; at $100,000 it is $22,364.55, $5,591.14 a quarter; at $200,000 it is $53,430.61, $13,357.65 a quarter. No flat percentage gives you those numbers — run your own profit through the calculator and pay the result four times a year.
Estimate only — not tax advice. Figures are for federal tax, tax year 2026, under the simplified assumptions on the About page (no credits, no state tax, simplified QBI). Your actual obligation depends on your full return, including withholding and credits. If a figure here ever disagrees with IRS.gov, IRS.gov is right.
Sources: IRS.gov — Topic 554, Self-Employment Tax (15.3% = 12.4% Social Security + 2.9% Medicare; 92.35% net-earnings factor; $400 threshold; one-half of SE tax deductible); IRS Schedule SE; SSA — 2026 Social Security wage base $184,500; IRS Rev. Proc. 2025-32 (2026 brackets and standard deduction $16,100 single); IRS.gov — Estimated Tax for Individuals. Tax figures from this site's engine, checked 6 Nov 2026. Live keyword check 6 Nov 2026: “self employed estimated tax calculator” / “1099 quarterly tax calculator 2026” SERP is small dedicated tools using the same 2026 figures.