How Self-Employment Tax Is Calculated — Step by Step

Self-employment tax (SECA) funds Social Security and Medicare for freelancers, independent contractors, and sole proprietors. Unlike W-2 employees who split FICA with their employer, self-employed workers pay both halves — the full 15.3%. The IRS applies this to 92.35% of net earnings rather than 100%, which partially compensates for the double burden.

Step-by-Step Calculation

Step 1Net profit × 92.35%
Step 2× 12.4% (SS, up to $184,500)
Step 3+ Net profit × 92.35% × 2.9%
Step 4= Total SE tax
DeductionSE tax ÷ 2 (reduces AGI)

Why 92.35%?

W-2 employeePays 7.65% FICA on gross wages
Employer also pays7.65% on same wages (separate)
Self-employedPays full 15.3% themselves
IRS adjustmentDeducts 7.65% (employer half) first
Result100% − 7.65% = 92.35%

Complete worked example — $83,400 net Schedule C profit, single filer

Net self-employment profit$83,400.00
Taxable SE earnings (× 92.35%)$83,400 × 0.9235 = $77,020.00
Social Security tax (12.4%)$77,020 × 12.4% = $9,550.48
Medicare tax (2.9%)$77,020 × 2.9% = $2,233.58
Total SE tax$11,784.06
50% SE deduction (reduces AGI)−$5,892.03
Federal income tax (taxable income $83,400 − $5,892 − $16,100 std. ded.)~$7,783
Total federal tax burden$11,784 + $7,783 = $19,567
Quarterly estimated payment$19,567 ÷ 4 = $4,892/quarter

Self-Employment Tax Reference Table — 2026

All figures use the IRS Schedule SE formula: net profit × 92.35% × 15.3%. The 50% deduction reduces your AGI before income tax is calculated — it does not reduce SE tax itself. IRS Publication 334 covers Schedule C rules for sole proprietors.

2026 self-employment tax by net income — single filer, no W-2 wages
Net SE income Taxable SE earnings (92.35%) SE tax (15.3%) 50% deduction Quarterly payment
$10,000$9,235$1,413$707$353
$25,000$23,088$3,532$1,766$883
$40,000$36,940$5,652$2,826$1,413
$55,000$50,793$7,771$3,886$1,943
$70,000$64,645$9,891$4,946$2,473
$83,400$77,020$11,784$5,892$2,946
$100,000$92,350$14,130$7,065$3,533
$150,000$138,525$21,194$10,597$5,299
$184,500 (SS cap)$170,335$26,061$13,031$6,515
$200,000$184,700*$27,025*$13,513$6,756

*At $200,000+, SS portion capped at $184,500 wage base; only 2.9% Medicare applies above. Additional 0.9% Medicare Tax kicks in above $200,000 (single). Quarterly estimate = SE tax only, not including federal income tax.

W-2 + 1099 Combined Income — How It Affects SE Tax

Workers with both W-2 employment income and self-employment income need to account for the $184,500 Social Security wage base across both income types. W-2 wages count first toward the cap — reducing or eliminating the Social Security portion of SE tax on 1099 income.

SE tax reduction when W-2 wages offset the SS wage base — 2026 ($184,500 cap)
W-2 wagesSE net profitSS taxable SE incomeSE taxSaving vs no W-2
$0$75,000$69,263$10,597
$50,000$75,000$69,263 (capped at $134,500 remaining)$10,597$0 (below cap)
$120,000$75,000$59,263 SS (only $64,500 of SE hits SS cap)$8,857$1,740 saved
$184,500+$75,000$0 SS (cap fully used)$4,345$6,252 saved

A worker with $184,500+ in W-2 wages owes no Social Security tax on self-employment income — only the 2.9% Medicare portion applies. At $75,000 SE income, this saves $6,252 compared to a freelancer with no W-2 income. This offset is calculated automatically on Schedule SE (Form 1040) — you do not manually calculate it, but understanding it helps with quarterly payment planning.

2026 Quarterly Estimated Tax Payment Dates

Self-employed workers who expect to owe $1,000 or more in federal taxes must make quarterly estimated payments to avoid an underpayment penalty. Payments cover both SE tax and federal income tax — not just SE tax alone.

Q1 Payment
Income: Jan 1 – Mar 31, 2026
Due: April 15, 2026
Q2 Payment
Income: Apr 1 – May 31, 2026
Due: June 16, 2026
Q3 Payment
Income: Jun 1 – Aug 31, 2026
Due: September 15, 2026
Q4 Payment
Income: Sep 1 – Dec 31, 2026
Due: January 15, 2027
Safe harbor rule — avoid the underpayment penalty Pay either 100% of your prior year tax liability (110% if prior year AGI exceeded $150,000) or 90% of the current year tax liability — whichever is smaller. If your income is unpredictable, the prior year safe harbor is the safer choice: calculate last year's total tax, divide by 4, and pay that amount each quarter regardless of current year income fluctuations.

S-Corporation Election — When It Saves SE Tax

S-Corp Tax Strategy for High-Income Self-Employed Workers

An S-Corporation election splits your self-employment income into two parts: a reasonable W-2 salary (subject to SE/payroll tax) and S-Corp distributions (not subject to SE tax). At $100,000 net income, paying yourself a $55,000 W-2 salary and taking $45,000 as a distribution saves approximately $6,885 in payroll tax ($45,000 × 15.3%).

$75,000 net income
~$3,000–$4,500/yr
Borderline — professional fees may offset savings
$100,000 net income
~$5,000–$7,000/yr
Strong case for S-Corp election
$150,000 net income
~$8,000–$12,000/yr
Clear net savings after compliance costs

The S-Corp election has compliance costs: separate payroll processing, quarterly payroll tax deposits, Form 941, annual W-2 issuance, Form 1120-S (separate S-Corp return), and typically a CPA fee. Total compliance costs are typically $2,000–$4,000 annually. The break-even point where S-Corp savings exceed costs is generally $65,000–$75,000 in annual net self-employment income. Below that threshold, a sole proprietorship or single-member LLC is usually simpler and cheaper. Consult a CPA before electing S-Corp status — "reasonable salary" requirements are enforced by the IRS and must reflect market compensation for your role.

Business Expenses That Reduce Self-Employment Tax

Every dollar of legitimate business expense reduces your Schedule C net profit — which reduces both your SE tax and your federal income tax. Unlike W-2 employees who cannot deduct most work expenses, self-employed workers deduct all ordinary and necessary business expenses before any tax is calculated.

Common Schedule C deductions and their SE tax impact — $80,000 gross revenue
Expense categoryExample annual amountSE tax reductionFederal tax reduction (22%)Total tax saved
Home office (dedicated room)$3,600$508$792$1,300
Vehicle (12,000 mi @ $0.67/mi)$8,040$1,135$1,769$2,904
Health insurance premiums$7,200$0*$1,584$1,584
Equipment / software$2,500$353$550$903
SEP-IRA contribution (25% of net)$15,000$0*$3,300$3,300
All deductions combined$36,340~$4,707~$7,995~$12,702

*Health insurance and SEP-IRA contributions are above-the-line adjustments to AGI, not Schedule C deductions — they reduce income tax but not SE tax. Vehicle mileage rate 67¢/mi for 2024; updated annually by IRS. Source: IRS Publication 334.

Self-Employment Tax — FAQ

How is self-employment tax calculated for 2026?

Four steps: (1) Multiply net SE income by 92.35% to get taxable SE earnings. (2) Apply 12.4% Social Security on the first $184,500. (3) Apply 2.9% Medicare on all taxable SE earnings. (4) Add both. Example: $75,000 profit × 92.35% = $69,263. SS: $69,263 × 12.4% = $8,589. Medicare: $69,263 × 2.9% = $2,009. Total SE tax = $10,597. You can deduct 50% ($5,299) from AGI, saving approximately $1,166 in federal income tax at 22% marginal rate. Use the calculator above for instant results.

What is the self-employment tax rate for 2026?

The SE tax rate is 15.3% — 12.4% Social Security + 2.9% Medicare — applied to 92.35% of net earnings. The 12.4% SS portion applies only to the first $184,500 of net earnings (the 2026 SSA wage base, confirmed by SSA COLA announcement). The 2.9% Medicare portion has no cap. High earners above $200,000 (single) pay an additional 0.9% Additional Medicare Tax on earnings above that threshold.

Why is self-employment tax applied to 92.35% of income, not 100%?

The 92.35% multiplier equals 1 minus 7.65% — the employer's half of FICA. W-2 employees pay 7.65% FICA; their employer pays a matching 7.65% separately as a business expense. Self-employed workers are both employer and employee, so the IRS allows them to deduct the employer-equivalent portion (7.65%) from net earnings before calculating SE tax — putting them on roughly equal footing with employees. The result: 100% − 7.65% = 92.35%.

Can I deduct self-employment tax?

Yes. You deduct 50% of your SE tax as an above-the-line adjustment on Form 1040, Schedule 1, Line 15. This reduces your AGI — which reduces your federal income tax and may reduce state income tax. It does not reduce the SE tax itself. On $10,597 in SE tax, you deduct $5,299 from AGI, saving approximately $1,166 at the 22% marginal federal rate. This is one of the few above-the-line deductions available to self-employed workers without needing to itemize.

How do quarterly estimated tax payments work?

Self-employed workers who expect to owe $1,000+ in federal taxes must pay quarterly. 2026 due dates: April 15 (Q1), June 16 (Q2), September 15 (Q3), January 15, 2027 (Q4). Each payment covers both SE tax and federal income tax for that quarter. The safe harbor: pay 100% of prior year tax liability (110% if prior year AGI exceeded $150,000) divided by 4. This protects against underpayment penalties even if current year income is higher than expected.

How does W-2 income affect self-employment tax?

W-2 wages count first toward the $184,500 SS wage base. If your W-2 wages are $120,000, only the first $64,500 of SE income ($184,500 − $120,000) is subject to the 12.4% Social Security rate. If W-2 wages exceed $184,500, no SS tax applies to any SE income — only 2.9% Medicare. At $75,000 SE income with $184,500+ in W-2 wages, you save approximately $6,252 in SE tax compared to a pure freelancer. This offset is calculated on IRS Schedule SE.

Can an S-Corporation reduce self-employment tax?

Yes. An S-Corp splits income into a W-2 salary (subject to payroll tax) and distributions (not subject to SE tax). At $100,000 net income with a $55,000 reasonable salary: SE/payroll tax applies only to $55,000 instead of $100,000 — saving approximately $6,885 ($45,000 × 15.3%). The break-even point is typically $65,000–$75,000 in net SE income after accounting for S-Corp compliance costs ($2,000–$4,000/year). Consult a CPA — the IRS requires a "reasonable salary" and monitors S-Corps that pay artificially low wages.

What business expenses reduce self-employment tax?

Any Schedule C business expense that reduces net profit also reduces SE tax. High-impact deductions: vehicle mileage (67¢/mile for 2024, updated annually), home office (dedicated workspace), equipment, software, professional services, and advertising. Health insurance premiums and retirement contributions (SEP-IRA up to 25% of net earnings; limit $70,000 for 2025) are above-the-line adjustments that reduce federal income tax but not SE tax. Every $1,000 in Schedule C deductions saves approximately $141 in SE tax (15.3% × 92.35%) plus income tax savings at your marginal rate.