Self-Employment Tax Calculator
2025 SE Tax, Quarterly Deadlines

What is self-employment tax?

Self-employment tax is the combined Social Security and Medicare tax obligation for individuals who work for themselves. In 2025, the rate is 15.3% of net self-employment income: 12.4% for Social Security and 2.9% for Medicare.

This is not a separate tax to income tax. It is in addition to income tax. A freelancer earning $100,000 net might pay $14,129 in SE tax plus $18,000 to $22,000 in federal income tax, plus state income tax on top of that. Understanding the full stack before setting your hourly rate and pricing your projects is essential for financial sustainability.

Why SE tax surprises most new freelancers

W-2 employees pay only the employee portion of FICA taxes: 6.2% Social Security and 1.45% Medicare, totalling 7.65%. Their employer quietly pays an equal amount. Freelancers pay both sides. The jump from 7.65% to 15.3% on the same income is the most common financial shock for professionals moving from employment to self-employment.

Because no tax is withheld automatically from freelance payments, the liability accumulates invisibly throughout the year. Without quarterly estimated tax payments, the year-end bill can be devastating. The IRS charges an underpayment penalty even if you ultimately receive a refund. The calculator above shows your quarterly obligation so you can set money aside from every invoice you collect.

The IRS SE tax formula

The IRS does not tax gross revenue directly. The calculation follows a specific sequence designed to account for the fact that the employer half of SE tax is itself deductible.

The 92.35% factor exists because employees deduct the employer's share of FICA from wages before the employee's share is calculated. The IRS replicates this for self-employed individuals through the adjustment. Without it, self-employed professionals would pay SE tax on a slightly higher base than employees with identical income.

2025 thresholds and key figures

Two thresholds change annually. The Social Security wage base increases each year in line with average wage growth. The additional Medicare tax threshold is fixed by statute and does not adjust for inflation.

2025 quarterly payment deadlines

The IRS requires estimated tax payments four times per year. Missing a deadline does not eliminate the obligation. It generates a penalty calculated per day on the unpaid amount. The safe harbor rule states that if your total estimated payments equal at least 100% of last year's tax liability (110% if your prior year AGI exceeded $150,000), you avoid the underpayment penalty even if you owe more at year end.

How to reduce your SE tax legally

Maximize deductible business expenses. Every dollar of legitimate business expense reduces your net profit, which reduces your SE taxable base directly. Common deductions that self-employed professionals miss include the home office deduction, professional development courses, half of the SE tax itself as an adjustment to gross income, and the self-employed health insurance deduction for premiums paid.

Contribute to a SEP-IRA or Solo 401(k). Retirement contributions for self-employed individuals are among the most powerful tax reduction tools available. A SEP-IRA allows contributions of up to 25% of net self-employment income (up to $69,000 in 2025). A Solo 401(k) allows both employee and employer contributions for potentially higher total deferrals. These contributions reduce your taxable income but do not reduce the SE tax base directly.

Structure as an S-Corporation at higher income levels. Once net self-employment income exceeds roughly $80,000 to $100,000, electing S-Corporation status can generate meaningful SE tax savings. An S-Corp owner takes a reasonable salary (subject to payroll taxes) and remaining profits as distributions (not subject to SE tax). This requires additional compliance work but can save thousands annually at higher income levels. Consult a tax professional before making this change.

Common mistakes with SE tax

Not setting aside tax from every invoice. The simplest and most reliable approach is to transfer a fixed percentage (typically 25 to 30%) of every client payment received into a dedicated tax savings account immediately upon receipt. This prevents the behavioral trap of spending money that is not yours and eliminates the anxiety of a large year-end bill.

Using gross revenue instead of net profit as the tax base. SE tax is calculated on net profit after business expenses, then further adjusted by 92.35%. Calculating on gross revenue significantly overestimates your liability and leads to over-saving for taxes while underinvesting in the business.

Missing the additional Medicare surcharge. Freelancers earning above $200,000 (single) or $250,000 (joint) owe an additional 0.9% on earnings above those thresholds. This is not withheld automatically and many professionals miss it at year end, leading to an unexpected additional liability. The calculator above applies this surcharge automatically when applicable.

Forgetting to include SE tax in your hourly rate calculation. The 15.3% SE tax is one of the most significant hidden costs of self-employment. If you did not account for it when setting your rate, you are effectively absorbing it as a reduction to your take-home pay. Use the hourly rate calculator with a 30 to 35% tax buffer to ensure your rate covers this obligation.