Self-Employment Tax Guide 2025
SE Tax, Quarterly Payments and Deductions

What is self-employment tax?

Self-employment tax is the Social Security and Medicare contribution required from anyone who earns more than $400 of net self-employment income in a year. For W-2 employees, this cost is split 50/50 between the employee and the employer. For freelancers and independent contractors, there is no employer -- so you pay both halves yourself.

The 2025 self-employment tax rate is 15.3% of net SE income, composed of 12.4% for Social Security and 2.9% for Medicare. This compares to the 7.65% that W-2 employees see on their pay stub -- but their employer is silently paying another 7.65% on their behalf. As a freelancer, that employer half is now your responsibility.

SE tax is calculated on Schedule SE and filed with your annual Form 1040. It is separate from income tax and applies before your standard or itemized deductions. This is one of the most common misconceptions for new freelancers -- the SE tax is not included in your income tax rate. It is an additional tax on top of income tax. Use the SE tax calculator to see both figures side by side.

How the 15.3% SE tax is calculated

The IRS does not apply the 15.3% rate directly to your net profit. The calculation uses the 92.35% adjustment to account for the deductibility of the employer portion of SE tax.

Concrete example at $100,000 net profit:

Net SE income: $100,000 x 0.9235 = $92,350. Social Security tax (12.4% on $92,350 up to $176,100 wage base): $11,451. Medicare tax (2.9% on all $92,350): $2,678. Total SE tax: $14,129. The naive calculation of $100,000 x 15.3% = $15,300 overstates the liability by $1,171. The 92.35% adjustment matters, and it is handled automatically by Schedule SE.

At higher income levels the Social Security component caps out. For 2025, the Social Security wage base is $176,100. Income above that threshold no longer pays the 12.4% Social Security portion -- only the 2.9% Medicare rate. Freelancers earning above $200,000 (single) or $250,000 (married) also pay an additional 0.9% Medicare surcharge on income above those thresholds.

Quarterly estimated tax payments

Freelancers must pay taxes quarterly rather than annually. The IRS requires estimated tax payments if you expect to owe at least $1,000 after withholding. Missing quarterly payments triggers a failure-to-pay penalty of 0.5% of the unpaid amount per month, plus the federal underpayment interest rate.

The simplest safe harbor approach: pay at least 100% of last year's total tax liability in four equal installments. If your prior-year adjusted gross income was above $150,000, pay 110% of last year's tax. This protects you from underpayment penalties even if your current-year income is higher than projected. Pay via IRS Direct Pay or EFTPS (the Electronic Federal Tax Payment System) for same-day confirmation and no processing fee. Make sure your hourly rate accounts for these quarterly payments in the tax buffer.

Top deductions to reduce SE tax liability

Business deductions reduce net profit, which reduces the base on which SE tax is calculated. Every dollar of legitimate business expense reduces both income tax and SE tax simultaneously. This double benefit makes deduction optimization especially valuable for freelancers.

Health insurance premiums are the most overlooked deduction for full-time freelancers. If you are not eligible for employer-sponsored coverage (including through a spouse's employer), 100% of your health, dental, and vision insurance premiums are deductible above the line. For a family paying $18,000 annually in premiums, this reduces taxable income by $18,000 and SE tax base by the same amount.

The SEP-IRA (Simplified Employee Pension) is the highest-impact retirement vehicle for most freelancers. You can contribute up to 25% of net SE income (after the SE tax deduction) up to a maximum of $70,000 in 2025. This contribution is 100% tax-deductible and reduces both income tax and the SE tax calculation simultaneously. A $20,000 SEP-IRA contribution reduces SE tax by approximately $3,065 (15.3% x 92.35% x $20,000) in addition to its income tax benefit.

These deductions interact with each other in a specific calculation order. Run your full numbers through the SE tax calculator to see your post-deduction liability, then feed that figure into the hourly rate calculator as your tax buffer input for a complete picture.

Business structure and SE tax

Sole proprietors and single-member LLC owners pay SE tax on 100% of net profit. S-corporations offer a partial workaround: the business pays a reasonable salary, and only that salary is subject to SE tax (as payroll taxes). Distributions above the salary are not subject to SE tax. For freelancers earning above $80,000-100,000 annually, the SE tax savings from electing S-corporation status can exceed the additional accounting costs within one to two years.

The S-corporation strategy requires paying yourself a "reasonable salary" that the IRS defines as comparable to what you would pay someone else to do the same work. Setting an unreasonably low salary to maximize distributions is a known audit trigger. For most freelancers earning $60,000-80,000, the savings do not justify the additional complexity and cost of payroll processing and corporate tax filing. Above $100,000, the math becomes compelling. Consult a CPA before changing business structure for tax purposes.