How self-employment tax is calculated
If you are paid on a 1099, no one withholds tax for you. You owe self-employment tax, which covers Social Security and Medicare, plus income tax on the same profit.
Self-employment tax is 15.3% of 92.35% of your net profit: 12.4% for Social Security, up to the 2026 wage base of $184,500, and 2.9% for Medicare with no cap. If that 92.35% figure is under $400, you owe no self-employment tax.
You also owe income tax on your profit. This estimate applies your top federal bracket and your state rate to your profit after deducting half of the self-employment tax.
Quarterly estimated tax payments
The IRS generally expects estimated payments if you will owe $1,000 or more for the year. This calculator splits the yearly estimate into four equal payments. The usual due dates are April 15, June 15, September 15 and January 15 of the next year, moved to the next business day when they fall on a weekend or holiday.
What this estimate leaves out
It does not include the standard deduction, the qualified business income deduction, credits, the extra 0.9% Medicare tax on high earners, or wages from a job that already count toward the Social Security wage base. Treat it as a savings target, not a tax return.
The formulas behind it
Every result cell is a plain spreadsheet formula, so you can check the math or rebuild it yourself.
| Cell | Result | Formula |
|---|---|---|
| B8 | Net profit | =B2-B3 |
| B9 | Earnings subject to SE tax | =B8*92.35% |
| B10 | Self-employment tax | =IF(B9<400, 0, MIN(B9,184500)*12.4%+B9*2.9%) |
| B11 | Income tax (estimate) | =(B8-B10/2)*(B4%+B5%) |
| B12 | Set aside this year | =B10+B11 |
| B13 | Each quarterly payment | =B12/4 |
| B14 | Share of income to save | =B12/B2 |
Sources
- IRS: Self-Employment Tax
- IRS: Estimated Taxes
- SSA: Contribution and benefit base
- IRS: Instructions for Schedule SE
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