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 to Mar 31, 2026
Due: April 15, 2026
Q2 Payment
Income: Apr 1 to May 31, 2026
Due: June 16, 2026
Q3 Payment
Income: Jun 1 to Aug 31, 2026
Due: September 15, 2026
Q4 Payment
Income: Sep 1 to 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 to $4,500/yr
Borderline: professional fees may offset savings
$100,000 net income
~$5,000 to $7,000/yr
Strong case for S-Corp election
$150,000 net income
~$8,000 to $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 to $4,000 annually. The break-even point where S-Corp savings exceed costs is generally $65,000 to $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 to $75,000 in net SE income after accounting for S-Corp compliance costs ($2,000 to $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.