Enter what you earn on the side. This estimates self-employment tax, federal income tax and state tax for the 2026 tax year, then shows the amount to move into savings each quarter. The numbers below are an example. Replace them with yours.
Apr 15, Jun 15, Sep 15, Jan 15, 2027This is an estimate for planning, not tax advice. It uses the 2026 self-employment tax rules: 15.3% on 92.35% of net profit, a Social Security wage base of $184,500, and 0.9% Additional Medicare Tax above $200,000 (single or head of household) or $250,000 (joint). Federal income tax uses the bracket you pick as a flat rate on profit after the deduction for half of your self-employment tax, and state tax is a flat rate on profit. Credits, other income and the phase-outs on the qualified business income deduction are not modeled.
Many people with a regular job and a small side business land between 25% and 40% of profit once self-employment tax, federal and state tax are added up. The calculator gives your number based on your bracket and state.
When you work for an employer, they pay half of Social Security and Medicare tax. On your own you pay both halves, which is 15.3% of 92.35% of your net profit. You can deduct half of it from your income when figuring income tax.
Generally yes if you expect to owe $1,000 or more for the year after withholding and credits. Paying a quarter of your set-aside amount by each due date helps you avoid underpayment penalties.
Yes. Social Security tax stops at the wage base, and your wages count toward it. A high salary means less of your side profit is subject to the 12.4% Social Security portion.