Quarterly Estimated Tax Calculator

This calculator helps self-employed individuals and small business owners estimate and pay their quarterly income taxes. It's crucial because the IRS requires you to pay income tax as you earn it, not just at year-end, to avoid penalties.

The calculator takes your expected self-employment income minus business expenses and adds self-employment tax: 15.3% of 92.35% of that net profit, with the Social Security part stopping at the $184,500 wage base less any W-2 wages you enter. Income tax is figured with the 2026 brackets on the profit plus W-2 wages, after half the self-employment tax, the standard deduction and the 20% qualified business income deduction on the self-employment profit (capped at 20% of taxable income and, with no employees, phased out between $201,750 and $276,750 of taxable income, $403,500 and $553,500 joint); tax credits are not subtracted. For the safe harbor, tell it whether last year's AGI was over $150,000. W-2 withholding and estimated payments already made come off the total, and the rest is divided by four to give each quarterly payment.

Always overestimate your income rather than underestimate to avoid underpayment penalties. Don't forget to account for self-employment taxes (Social Security and Medicare) which are often overlooked when calculating estimated taxes.