Withholding & Planning · 2025
Self-Employment Tax Calculator
Enter your net self-employment income to see your 2025 Schedule SE tax — the Social Security portion, Medicare portion, and the deductible half that reduces your income tax, shown step by step.
Your information
Net profit from Schedule C, F, or K-1 — after all business expenses
Your employer withheld SS on these — they reduce the remaining $176,100 SS wage base headroom
Informational only — not professional tax advice.
Enter your net self-employment income to see your Schedule SE tax — Social Security portion, Medicare portion, the deductible half, and your effective SE rate, all shown step by step.
Methodology
How Schedule SE self-employment tax is calculated
Self-employment tax is computed on Schedule SE (Form 1040) and covers both the employee and employer shares of Social Security and Medicare (FICA). The combined FICA rate is 15.3%: 12.4% for Social Security (capped at the annual wage base) and 2.9% for Medicare (no cap). Rather than pay 15.3% on 100% of net SE income, Schedule SE first reduces net SE income by a 7.65% factor, leaving 92.35% subject to the full 15.3% rate.
Formula
SE earnings = Net SE income × 0.9235
Social Security tax = min(SE earnings, SS wage base − other wages) × 12.4%
Medicare tax = SE earnings × 2.9%
SE tax (Schedule SE) = Social Security tax + Medicare tax
Deductible half = SE tax × 50% (Schedule 1, line 15; IRC §164(f))
Additional Medicare Tax = max(0, wages + SE earnings − threshold) × 0.9%
(Form 8959; not included in deductible half)Tax year scope
This calculator uses 2025 tax year rates: a 12.4% Social Security rate on earnings up to the $176,100 wage base (SSA.gov, October 2024), and a 2.9% Medicare rate on all SE earnings per IRS Schedule SE instructions. The 0.9% Additional Medicare Tax threshold is set by IRC §3101(b)(2) and is not inflation-adjusted.
Stated assumptions and limitations
- Net profit only. Enter net profit after all deductible business expenses. This calculator does not model business expense deductions — those reduce net SE income before Schedule SE applies.
- Single tax year. Results assume all SE income falls in tax year 2025. Multi-year or installment scenarios are out of scope.
- Additional Medicare Tax is estimated. The 0.9% Additional Medicare Tax depends on Modified Adjusted Gross Income (MAGI), which includes investment income and other adjustments not modeled here. This calculator uses wages + SE earnings as a simplified MAGI proxy.
- No income tax modeled. The deductible half reduces your AGI and therefore your income tax liability — but the income tax savings depend on your marginal income tax rate, which this tool does not calculate. Use the Federal Income Tax Calculator alongside this tool for a fuller picture.
Last reviewed: January 2025. Social Security wage base and FICA rates reviewed annually after SSA publishes the COLA fact sheet (typically October).
Frequently asked questions
What is self-employment tax?
Self-employment (SE) tax covers Social Security and Medicare taxes for people who work for themselves. Employees split these costs with their employer — 7.65% each — but self-employed individuals pay both halves, for a combined rate of 15.3%. To account for the employer half, the IRS lets you deduct 50% of your SE tax as an above-the-line adjustment to gross income (Schedule 1, line 15). SE tax applies to net SE income of $400 or more.
Why is SE tax calculated on 92.35% of my net income, not 100%?
The 92.35% factor compensates for the employer deduction that employees get implicitly. Employees pay 7.65% on their wages, but the employer also pays 7.65% on top — the employee never sees that amount as taxable income. Self-employed individuals earn both shares as income, so Schedule SE reduces net SE income by 7.65% (the 'employer half') before applying the 15.3% combined rate. The result: 100% − 7.65% = 92.35%. Mathematically, this is equivalent to paying 14.13% on 100% of net income.
What is the deductible half of self-employment tax?
The deductible half is 50% of your Schedule SE tax (the Social Security + Medicare portions only — not the Additional Medicare Tax). You claim it on Schedule 1, line 15, as an above-the-line adjustment to gross income, which means it reduces your AGI and therefore your federal income tax liability even if you don't itemize deductions. For example, if your SE tax is $10,000, your deductible half is $5,000 — reducing your taxable income by $5,000 and saving you income tax on that amount at your marginal rate.
Do I owe self-employment tax if I also have a W-2 job?
Yes — SE tax is computed on net SE income regardless of other employment. However, if you also have W-2 wages, your employer already withheld Social Security on those wages, which counts toward the annual Social Security wage base ($176,100 in 2025). SE tax applies Social Security only to the remaining headroom in that wage base. For example, if you have $100,000 in W-2 wages, only the first $76,100 of SE earnings is subject to the 12.4% Social Security rate — though all SE earnings remain subject to the 2.9% Medicare tax.
Related tools
Calculate your quarterly estimated tax payments using the safe harbor method — shows the annual and per-quarter amounts with IRS due dates and underpayment threshold cited.
Open tool →W-4 Withholding EstimatorEstimate how much federal tax will be withheld from your paycheck based on your W-4 elections — IRS Publication 15-T Percentage Method, every step shown.
Open tool →Federal Income Tax CalculatorEnter your income and filing status to see exactly how the 2025 U.S. tax brackets apply — marginal rate, effective rate, and every dollar of tax shown bracket by bracket.
Open tool →