Self-Employment Tax Calculator
The tax employees never see: Social Security and Medicare on net self-employment earnings — both the worker's half and the employer's half — plus the deductible half that softens the blow at income-tax time.
Self-employment tax
Example: $100,000 net earnings, 2026 → $14,129.55 SE tax; $7,064.78 deductible.
Read the guide first if the concept is new: Self-Employment Tax, Explained traces one 2026 example from profit through both halves, the deductible half, income tax and the quarterly rhythm. This page documents the calculator itself — what the formula does with each input, where each portion stops, and how to read the result lines. More explainers are collected under Guides.
The computation, step by step
The engine applies one formula, in a fixed order, to the single number you enter. On $100,000 of net self-employment earnings in 2026 (single filer — the SE tax itself does not vary by filing status, as the FAQ explains):
| Step | Rule the engine applies | Amount |
|---|---|---|
| Net earnings | Schedule C profit, as entered | $100,000 |
| SE tax base | 92.35% of net earnings | $92,350.00 |
| Social Security | 12.4% of the base, up to the $184,500 wage base | $11,451.40 |
| Medicare | 2.9% of the whole base, no cap | $2,678.15 |
| Additional Medicare | 0.9% of the base above $200,000 | $0.00 |
| Self-employment tax | The three portions added | $14,129.55 |
| Deductible half | Half of Social Security + Medicare (surtax excluded) | $7,064.78 |
Two things in that table are easy to miss. The base is 92.35% of profit, not all of it — so the headline 15.3% works out to 14.13% of net earnings here, and to 14.13% of profit for anyone under the wage base. And the deductible half is not half of the total: it is half of the Social Security and Medicare portions only, which only matters once the surtax is non-zero. Every figure on this page is computed at build time by the same tested engine as the calculator above, so the copy cannot drift from the tool.
What each input does
Net self-employment earnings is the only dollar figure the formula uses, and it must be profit — revenue minus the business expenses reported on Schedule C. Entering gross receipts produces a wildly high answer, because every expense dollar left in the input is taxed at the full 15.3% of its 92.35% share. The engine requires a positive number: zero or a loss produces no computation rather than a zero result, because a year with no net self-employment profit has no Schedule SE base to tax, and the optional methods that can apply in low-income years are not modeled.
Tax year selects which entry in the site's data file the engine reads. The rates and the 92.35% share do not change across the supported years; what moves is the Social Security wage base, and with it the profit level at which the Social Security portion stops growing:
| Tax year | Combined rate | Taxable share | Social Security wage base | Net earnings where the cap is reached |
|---|---|---|---|---|
| 2026 | 15.3% | 92.35% | $184,500 | $199,783 |
| 2025 | 15.3% | 92.35% | $176,100 | $190,688 |
Below the lower of those cap points the year makes no difference to the result; above it, the year with the higher wage base means more Social Security tax on the same profit. When the following year's figures are published they are added to the same data file and this table, the calculator, and every worked example on the page update together.
Four earners across the wage base
The formula behaves differently in three regions: below the wage base, between the wage base and the surtax threshold, and above both. The rows below — all 2026, all single filers, all computed by the engine — put one earner in each region, plus a small side income:
| Earner | Net earnings | SE base | Social Security | Medicare | Surtax | SE tax | Deductible half | % of profit |
|---|---|---|---|---|---|---|---|---|
| Side income | $40,000 | $36,940 | $4,580.56 | $1,071.26 | $0.00 | $5,651.82 | $2,825.91 | 14.13% |
| Full-time freelancer | $100,000 | $92,350 | $11,451.40 | $2,678.15 | $0.00 | $14,129.55 | $7,064.78 | 14.13% |
| Over the wage base | $200,000 | $184,700 | $22,878.00 | $5,356.30 | $0.00 | $28,234.30 | $14,117.15 | 14.12% |
| Over the surtax threshold | $320,000 | $295,520 | $22,878.00 | $8,570.08 | $859.68 | $32,307.76 | $15,724.04 | 10.1% |
Side income, $40,000. Every portion is a straight percentage of the $36,940 base: $4,580.56 of Social Security and $1,071.26 of Medicare, $5,651.82 in all — 14.13% of profit, the same share as every other earner under the cap. A small figure does not mean a small rate: the tax is proportional from the first dollar of base, and the calculator makes no allowance for the statutory minimum below which Schedule SE is not required.
Full-time freelancer, $100,000. The flagship example from the table above. The base of $92,350.00 is still under the $184,500 wage base, so Social Security and Medicare both apply to all of it and the surtax is $0.00.
Over the wage base, $200,000. The base is $184,700.00, above the $184,500 wage base, so Social Security is charged on the wage base only — $22,878.00, exactly what the engine computes for any higher earner in 2026. Medicare has no such stop and takes $5,356.30 on the full base. The base is still under the $200,000 surtax threshold — it is the 92.35% base, not the profit, that the engine compares against the threshold — so the surtax remains $0.00, and the effective rate on profit has fallen to 14.12%.
Over the surtax threshold, $320,000. Social Security is unchanged from the previous earner at $22,878.00 — the cap has already done its work. Medicare rises to $8,570.08, and now the base of $295,520.00 exceeds $200,000, so the 0.9% Additional Medicare surtax applies to the $95,520.00 above it: $859.68. Note the deductible half here — $15,724.04 — is half of $31,448.08, not half of the $32,307.76 total, because the surtax sits outside it.
Where Social Security stops and Medicare does not
The wage base is a ceiling on the base, not on profit. The engine compares the 92.35% base against $184,500 and charges 12.4% on the smaller of the two, which is why the cap is reached at about $199,783 of net earnings ($184,500 ÷ 92.35%) rather than at $184,500 itself. The same arithmetic places the $200,000 surtax threshold at about $216,567 of net earnings. Between those two points the marginal rate on additional profit is just the Medicare rate on the 92.35% share; above the second point the surtax joins it. Medicare itself never stops: every dollar of base carries the 2.9% rate however high earnings go, which is what makes the effective rate flatten rather than fall toward zero as profit grows.
The computation takes no filing status, which is why the form does not ask for one; the $200,000 Additional Medicare threshold it applies is the single-filer figure, used for everyone. Joint and separate filers have different thresholds under the Form 8959 rules, which are not modeled here, so the surtax line is an estimate for anyone not filing as single. Below the single threshold the difference cannot appear at all, because the surtax is zero.
The deductible half, priced
"Half is deductible" is easy to misread. The full $14,129.55 is owed on the flagship example; what comes back is a deduction of $7,064.78 against income, not a payment. Its value depends on the income-tax bracket it lands in. Run the same 2026 single filer through the bracket engine with profit as the only income and the $16,100 standard deduction: without the deduction, federal income tax is $13,170.00; with it, $11,615.75. The deduction is worth $1,554.25 in income tax — a 22% marginal rate applied to the deduction, not the deduction itself. The order of operations is fixed: SE tax is computed first from profit, and the half then reduces taxable income on the income-tax side only. Nothing feeds back into the SE tax, and the 0.9% surtax is excluded from the half entirely.
Reading the output, and four misreadings
The result box shows the total first, then four lines: the taxable base, the Social Security portion, the Medicare portion, and the deductible half. Four points about those lines:
- The Medicare line includes the surtax. It is the 2.9% Medicare tax plus any 0.9% Additional Medicare surtax, added together. Below the threshold it equals 2.9% of the base exactly; above it, the line grows faster than the base does.
- The total is not 15.3% of what you entered. It is 15.3% of the 92.35% base — 14.13% of profit below the cap, and less above it. Checking the result by multiplying profit by the headline rate will always disagree with the engine.
- The total is not your tax bill. Federal income tax is computed separately on taxable income and added. For the $100,000 example, single with the standard deduction, the combined federal figure is $25,745.30: $14,129.55 of SE tax plus $11,615.75 of income tax on $76,835.23 of taxable income.
- The deductible half is not subtracted from anything shown here. It is reported for use on the income-tax side; the SE tax total stands as displayed.
From this figure to quarterly payments
No one withholds tax from self-employment income, so the federal rules collect it during the year through Form 1040-ES installments — four for 2026, due April 15, 2026; June 15, 2026; September 15, 2026; January 15, 2027. The required annual payment is the lesser of 90% of the current year's expected tax or 100% of the prior year's tax (110% when prior-year AGI exceeds $150,000), and no installments are required when the expected balance after withholding is under $1,000. For the $100,000 example with no withholding and no prior-year figures entered, the 90% harbor on the $25,745.30 combined federal tax works out to $5,792.69 per installment. The Quarterly Tax Calculator runs both harbors for any mix of self-employment profit, W-2 withholding and prior-year tax, and the Federal Income Tax Calculator prices the income-tax side alone.
What this calculator leaves out
The scope is the federal self-employment tax on a single profit figure. The following are real and excluded by design rather than modeled badly:
- W-2 wages in the same year — the wage base is shared with Social Security wages already reported on a W-2; the engine treats it as fully available.
- Filing-status surtax thresholds — the surtax is estimated at the single-filer threshold for everyone.
- The statutory minimum and the optional methods — the floor below which Schedule SE is not required and the farm and non-farm optional methods for low-income years.
- Entity structure — the formula assumes sole-proprietor or partner profit reported on Schedule SE.
- Income tax, credits and state taxes — the income-tax side is a separate computation; credits and state or local taxes are not modeled anywhere on this site.
Frequently asked questions
Why do the self-employed pay 15.3% instead of 7.65%?
Employees split FICA with their employer: each pays 6.2% Social Security and 1.45% Medicare. When you are both the worker and the business, you pay both halves — 12.4% + 2.9% = 15.3%. The consolation is that the employer-equivalent half is deductible against your income tax.
What are "net self-employment earnings"?
Your self-employment revenue minus business expenses — the Schedule C profit, not gross receipts. The tax then applies to 92.35% of that figure, a statutory adjustment standing in for the employer half an employee would never see as wages.
Does this replace income tax?
No — it is in ADDITION to federal income tax. Self-employment tax funds Social Security and Medicare; income tax is computed separately on your taxable income (after deducting half the SE tax). On the $100,000 example for 2026, a single filer taking the standard deduction owes $14,129.55 of SE tax plus $11,615.75 of income tax. Budgeting both, plus quarterly estimated payments, is the core discipline of self-employment finances.
Is there a cap?
The Social Security portion stops at the annual wage base — $184,500 for 2026, which the SE base reaches at about $199,783 of net earnings; the calculator applies the cap for the year you select. The 2.9% Medicare portion has no cap. An additional 0.9% surtax also applies to the base above a threshold that depends on filing status, and this calculator estimates it at the $200,000 single-filer threshold. High-earning freelancers keep paying Medicare all the way up.
Why is the "Medicare portion" line more than 2.9% of the base at high incomes?
Because that line combines two taxes: the 2.9% Medicare tax on the whole base and the 0.9% Additional Medicare surtax on the part of the base above $200,000. On $320,000 of net earnings in 2026, for a single filer (the threshold this calculator assumes), the engine computes $8,570.08 of Medicare plus $859.68 of surtax, and the result line shows their sum. Below the threshold the surtax is zero and the line is exactly 2.9% of the base.
Is the deductible half a refund of half the tax?
No. The full self-employment tax is owed. The deductible half is an income-tax deduction: it lowers the taxable income your brackets apply to, so its value is roughly the deduction times your marginal rate, not the deduction itself. On the $100,000 example (single, standard deduction, 2026) the $7,064.78 deduction lowers federal income tax by $1,554.25. It never reduces the SE tax, and the surtax is excluded from it.
Does my filing status change the self-employment tax?
Not the core computation: the 92.35% base, the 12.4% Social Security portion, the wage base and the 2.9% Medicare portion are the same for every filing status, which is why the form above does not ask for one. Filing status matters only for the 0.9% surtax threshold, which this calculator estimates at the $200,000 single-filer figure, and for the income-tax side that the deductible half feeds into.
What if I also have W-2 wages?
The Social Security wage base is one annual ceiling shared between the Social Security wages on your W-2 and your self-employment earnings. This calculator treats the wage base as fully available to self-employment earnings, so with W-2 wages in the same year its Social Security line can overstate what Schedule SE would compute. Medicare has no ceiling, so that portion is unaffected.
Which tax year should I select?
The year the earnings belong to. Across the supported years, what moves is the Social Security wage base: $184,500 for 2026, $176,100 for 2025. The rates and the 92.35% share are the same in each supported year, so below the cap the tax on a given profit is identical from year to year — the year matters once earnings approach the wage base.
Not tax advice: a planning estimate. It excludes income tax itself, state taxes, the statutory minimum below which Schedule SE is not required, coordination of the wage base with any W-2 wages you also earn, filing-status differences in the 0.9% surtax threshold, the optional methods for low-income years, and entity-structure effects (an S-corp changes this math). Consult a tax professional for your situation. Values are processed locally in your browser and never transmitted. See the disclaimer and the methodology page.