1099 quarterly tax estimator: self-employment tax, due dates and safe harbor

• Self-employment tax is the Social Security and Medicare tax you pay yourself, with no employer sharing it. It is 15.3% of 92.35% of net profit: 12.4% for Social Security, up to the $184,500 wage base for 2026, and 2.9% for Medicare. Wages from a job count against the same wage base first.
• Half of the self-employment tax is deducted from income before income tax. Income tax uses the same 2026 brackets and standard deduction as the Paycheck lab.
• Estimated payments are due on four dates for tax year 2026: April 15, June 15 and September 15 of 2026, and January 15, 2027. The January payment is not required if you file by February 1, 2027 and pay the balance with the return.
• The safe harbor is the amount that avoids the underpayment penalty: the smaller of 90% of this year's tax and 100% of last year's tax. If last year's adjusted gross income was over $150,000, the prior-year share is 110%. The lab shows both the full estimate and the safe-harbor amount.
• The set-aside rate is the tax your 1099 work adds, self-employment tax plus the extra income tax, divided by your net profit.

Net earnings are $24,000 times 92.35%, or $22,164. Self-employment tax at 15.3% is $3,391. Half of that, $1,696, comes off income, leaving $22,304 of adjusted gross income and $6,204 of taxable income after the $16,100 standard deduction. Income tax on that is $620. The 2026 total is $4,012, which is $1,003 a quarter and about 17% of each payment. With $4,000 withheld from a job instead, the same lab shows a smaller quarterly amount because withholding counts as tax already paid.

• The lab covers tax year 2026 only. Dates and limits change each year.
• The qualified business income (QBI) deduction is not modeled. It can lower income tax for many self-employed people, so the estimate can run higher than the tax you owe.
• Additional Medicare tax, credits, state and local tax are not modeled.
• Income and expenses are spread evenly. Uneven income can change when payments are due, and Form 2210 has an annualized method for it.
• Net profit is after business expenses. A mistake in expenses carries straight into the tax.

Finance Quest is educational. It is not financial advice, and no calculator here knows your full situation.

People on a 12% federal bracket often set aside 12%. Self-employment tax adds 15.3% of 92.35% of net profit on top, so the share of each payment that goes to tax is often well above the bracket. In the example, a taxable income of $6,204 sits in the 10% bracket, and the set-aside is still about 17% of profit because self-employment tax is most of the bill.

• Side hustle ROIFind the real hourly return after costs and self-employment tax.
• Tax deductionsCompare standard against itemized on your real numbers.
• PaycheckEstimate take-home pay with tax and deduction assumptions.