Self-Employment Tax Explained: What Freelancers Owe in 2025
Self-employed workers pay both halves of FICA — 15.3% on 92.35% of net earnings. Here's exactly how the self-employment tax works, what deductions reduce your bill, and how to plan quarterly estimated payments.
When you're an employee, your employer quietly pays half your Social Security and Medicare taxes on your behalf — and you pay the other half through payroll withholding. As a freelancer, contractor, or sole proprietor, there's no employer. You pay both halves yourself. That's the self-employment (SE) tax: an additional 15.3% on top of ordinary income tax that catches most first-year freelancers off guard.
The good news: there are real deductions that reduce your taxable income, and with some planning, the bite is manageable. This guide explains the mechanics, the maths, and the strategies.
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What is self-employment tax?
The self-employment tax is the US federal tax that funds Social Security and Medicare for self-employed workers. For employees, FICA is split 50/50: the employer pays 7.65% and the employee pays 7.65%. Self-employed workers are both the employer and the employee, so they owe the full 15.3%.
The SE tax breaks down as:
- Social Security: 12.4% on net SE income up to the wage base cap ($176,100 in 2025)
- Medicare: 2.9% on all net SE income, with no cap
High earners also owe an additional 0.9% Additional Medicare Tax on wages and SE income above $200,000 (single filer) or $250,000 (married filing jointly). This is reported on Form 8959.
The 92.35% factor — why you don't pay on 100% of income
The IRS applies SE tax to 92.35% of net self-employment income, not 100%. This adjustment exists because employees compute their wages before the employer's share of FICA is added. The 92.35% figure is 100% − 7.65% (the "employer" half of FICA you're effectively deducting from your own earnings).
Example: $80,000 net SE income (single filer, 2025)
- SE taxable: $80,000 × 92.35% = $73,880
- SS tax: $73,880 × 12.4% = $9,161
- Medicare tax: $73,880 × 2.9% = $2,143
- Total SE tax: $11,304
That $11,304 is separate from — and in addition to — your federal income tax.
Deductions that reduce your income tax (not the SE tax itself)
The SE tax itself is fixed by the formula above. But three deductions significantly reduce how much income tax you pay on top of it:
1. Deduction for half of SE tax
You can deduct 50% of your SE tax as an adjustment to income (on Schedule 1, Form 1040 — not an itemised deduction). In the example above, that's $11,304 ÷ 2 = $5,652 off your adjusted gross income (AGI).
2. The Qualified Business Income (QBI) deduction
Most sole proprietors and single-member LLCs qualify for a 20% deduction on net qualified business income under Section 199A. This is a significant deduction introduced by the 2017 Tax Cuts and Jobs Act. On $80,000 income: $16,000 deducted from taxable income. There are phase-out thresholds for certain "specified service" businesses (law, consulting, financial services) above $197,300 (single, 2025).
3. Standard deduction
The 2025 standard deduction for single filers is $15,000 ($30,000 MFJ). Combined with the half-SE deduction and QBI, you can remove a substantial portion of gross income before calculating income tax:
| Item | Amount |
|---|---|
| Gross self-employment income | $80,000 |
| − ½ SE tax deduction | −$5,652 |
| − QBI deduction (20%) | −$16,000 |
| − Standard deduction | −$15,000 |
| Federal taxable income | $43,348 |
At $43,348, the 2025 single-filer income tax (applying 10%/12% brackets) is approximately $5,002. Total federal tax: $5,002 + $11,304 SE tax = $16,306 — an effective total rate of about 20.4% on $80,000.
Quarterly estimated tax payments
Unlike employees who have tax withheld each pay period, freelancers must pay taxes in advance through quarterly estimated payments. Failing to do so typically results in an underpayment penalty (calculated as approximately 7–8% annualised, adjusted quarterly by the IRS).
The four 2025 payment deadlines are:
- Q1: 15 April 2025 (income January–March)
- Q2: 16 June 2025 (income April–May)
- Q3: 15 September 2025 (income June–August)
- Q4: 15 January 2026 (income September–December)
The safe harbour rule: to avoid penalties, you can pay either 100% of last year's total tax liability (110% if AGI was above $150,000) OR 90% of your current year's actual liability, whichever is smaller. Many freelancers find the prior-year method simpler when income is variable.
Pay via IRS Direct Pay (free), EFTPS, or the IRS2Go app. Use Form 1040-ES to calculate the correct amounts.
Strategies to reduce your total SE tax burden
Maximise retirement account contributions
Contributions to a SEP-IRA (up to 25% of net SE income, max $70,000 in 2025) or a Solo 401(k) (employee contributions up to $23,500 + employer contributions up to 25% of net SE income) reduce your net SE income. A lower net SE income means lower SE tax and lower income tax simultaneously. At $80,000, a $16,000 SEP-IRA contribution reduces SE tax by about $2,261 and saves income tax on top of that.
Elect S-Corporation status
Once SE income reliably exceeds approximately $80,000–$100,000, forming an S-Corp can reduce SE taxes substantially. You pay yourself a "reasonable salary" — which is subject to FICA — and take the remaining profit as a distribution (not subject to SE tax). The setup and payroll administration costs need to be weighed against the SE tax savings.
Maximise legitimate business deductions
SE tax is calculated on net self-employment income (revenue minus business expenses). Every legitimate deduction — home office (Form 8829), equipment, software, professional development, business travel, health insurance premiums — reduces the base on which SE tax is calculated. Business deductions reduce both income tax and SE tax, making them doubly valuable.
Health insurance deduction
Self-employed workers who pay for their own health insurance can deduct 100% of premiums (and dental/long-term care premiums) as an above-the-line deduction. This is separate from the QBI deduction and reduces AGI directly.
International equivalents
United Kingdom — Class 4 National Insurance
UK self-employed workers don't pay Class 1 NI (employee/employer). Instead, profits above £12,570 are subject to Class 4 NI: 6% on profits from £12,570 to £50,270, and 2% above. Class 2 NI (a flat weekly charge) was abolished from April 2024. UK self-employed workers typically pay annual income tax plus Class 4 NI through the self-assessment system, with a balancing payment each January.
Canada — CPP contributions
Self-employed Canadians pay both the employee and employer portions of Canada Pension Plan (CPP) contributions — 11.9% combined on earnings between $3,500 and $71,300 (CPP1), plus 8% on earnings between $71,300 and $81,200 (CPP2) for 2025. Half of these contributions is deductible from federal taxable income. Employment Insurance (EI) is optional for self-employed Canadians.
Australia — sole traders
Australian sole traders pay income tax and the Medicare levy (2%) on net business income, but there's no self-employed equivalent of SE tax. The Super Guarantee (11.5% in 2025) is not deducted from a sole trader's income — it's paid in addition to invoiced fees and is the business's (i.e. your) obligation when you eventually retire. Quarterly GST and PAYG instalment reporting applies to most active businesses.
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Summary
Self-employment tax is not optional, but it is manageable with the right structure. The key levers: maximise the QBI deduction, contribute aggressively to a SEP-IRA or Solo 401(k), deduct all legitimate business expenses, and stay ahead of quarterly estimated payment deadlines. Above ~$100,000 in consistent SE income, an S-Corp election often pays for itself within the first year.