US Quarterly Estimated Tax Calculator (2026)

Worked example

Example: single freelancer, $80,000 net Schedule C profit, no other income, no withholding, 2025 total tax $10,000, 2025 AGI $70,000.

1. SE tax: $80,000 × 0.9235 = $73,880 net earnings. All below the $184,500 wage base, so SE tax = $73,880 × 15.3% = $11,304.
2. Half-SE deduction: $11,304 ÷ 2 = $5,652.
3. AGI: $80,000 − $5,652 = $74,348.
4. Taxable income: $74,348 − $16,100 standard deduction = $58,248.
5. Income tax (2026 single): 10% × $12,400 = $1,240; 12% × $38,000 = $4,560; 22% × $7,848 = $1,726.56. Total = $7,527.
6. Total projected tax: $7,527 + $11,304 = $18,831.
7. Safe harbor: 90% of current year = $16,948; prior-year 100% = $10,000 (AGI under $150,000, so 100% not 110%). Take the smaller = $10,000.
8. Quarterly payment: $10,000 − $0 withholding = $10,000 ÷ 4 = $2,500 per quarter.

Paying $2,500 each quarter meets the prior-year safe harbor and avoids the underpayment penalty, though about $8,831 will still be due when the return is filed. If the 2025 AGI had topped $150,000 the prior-year target would be 110% = $11,000. To avoid the April balance, base payments on the current-year $18,831 figure instead (roughly $4,708 per quarter).

How it is calculated, step by step

1. 1. Compute self-employment tax. Multiply net SE profit by 0.9235 to get net earnings from self-employment. On the amount up to the $184,500 Social Security wage base apply 12.4%; on the full net earnings apply 2.9% Medicare (no cap). The sum is your SE tax (combined rate 15.3% below the wage base).
2. 2. Take the above-the-line deduction for one-half of the SE tax from step 1.
3. 3. Build AGI = net SE profit + other income minus one-half SE tax (minus any other above-the-line adjustments).
4. 4. Subtract the standard deduction for the filing status ($16,100 single / $32,200 MFJ / $24,150 HoH / $16,100 MFS for 2026) to get taxable income.
5. 5. Apply the 2026 ordinary income tax brackets to taxable income to get the income tax.
6. 6. If wages plus SE earnings exceed the Additional Medicare threshold ($200,000 single/HoH, $250,000 MFJ, $125,000 MFS), add 0.9% on the excess.
7. 7. Total projected tax = income tax + SE tax + any Additional Medicare tax.
8. 8. Compute the safe harbor: the smaller of 90% of current-year total tax, or 100% of last year's total tax (110% if prior-year AGI exceeded $150,000, or $75,000 if MFS).
9. 9. Required annual estimated payment = safe-harbor amount minus expected withholding. If the remaining balance you would owe is under $1,000, no estimates are required.
10. 10. Divide the required annual payment by 4 for each quarterly installment, due April 15, June 15, September 15 (2026) and January 15 (2027). Cumulative paid by each deadline should reach 22.5%, 45%, 67.5% and 90% of the target.

Why this differs from a simple income tax estimate

Quarterly estimated tax is not just income tax split into four. For the self-employed it bundles two separate taxes into every payment: ordinary income tax and self-employment (SE) tax, the 15.3% that replaces the Social Security and Medicare withholding an employer would normally handle. SE tax alone can be the larger of the two for middle-income sole proprietors, and it is easy to forget because there is no paycheck deducting it.

The calculator also models the deduction for one-half of SE tax, which lowers your AGI before income tax is applied, so the two taxes interact. A generic tax estimator that ignores SE tax will understate what a freelancer owes by thousands of dollars. That is exactly the gap that produces surprise April bills and underpayment penalties.

The safe harbor: how to avoid a penalty

The IRS charges an underpayment penalty (effectively interest) if you do not prepay enough during the year. You are protected if, through withholding and estimates, you pay the smaller of 90% of this year's total tax or 100% of last year's total tax. If your prior-year AGI was over $150,000 ($75,000 if married filing separately), the prior-year figure rises to 110%. These safe-harbor percentages are set by statute and do not change from year to year.

The prior-year route is powerful because it is a fixed, known number: if your 2025 total tax was $10,000 and 2025 AGI was under $150,000, paying $10,000 across 2026 blocks the penalty no matter how much your income grows. The trade-off is a possible balance due at filing. The 90%-of-current-year route minimizes that balance but requires forecasting income you may not know yet. The calculator shows both so you can choose.

Note that estimates must be roughly even across quarters. The cumulative safe-harbor bar is 22.5%, 45%, 67.5% and 90% by each deadline, so skipping Q1 and catching up in Q4 can still trigger a penalty for the early quarters.

2026 due dates and how payments are timed

The four 2026 installments are due April 15, 2026, June 15, 2026, September 15, 2026, and January 15, 2027. For the 2026 tax year every date falls on a weekday, so none shift. The periods are still uneven: Q1 covers three months, Q2 only two, Q3 three, and Q4 four, which is why the June deadline sneaks up on people.

2025 vs 2026 figure note: the 90%/100%/110% safe-harbor rules and the four calendar deadlines are unchanged, but the underlying numbers rose with inflation. The single standard deduction went from $15,750 (2025) to $16,100 (2026), MFJ from $31,500 to $32,200, and HoH from $23,625 to $24,150; the Social Security wage base climbed from $176,100 to $184,500, and every income-tax bracket widened. So the same profit yields a slightly lower 2026 tax bill than in 2025.

Withholding is treated as paid evenly across the year regardless of when it was actually withheld, but estimated payments count when you actually pay them. If your income is lumpy (a big Q3 contract, for instance), the annualized income installment method on Form 2210 can reduce early-quarter penalties by matching payments to when income was earned. You can pay online free via IRS Direct Pay or EFTPS, or mail a Form 1040-ES voucher.

Who needs to pay and who can skip it

You must make estimated payments if you expect to owe at least $1,000 after subtracting withholding and refundable credits, and your withholding is less than the safe-harbor amount. If you owe under $1,000 at filing, no estimates are required and no penalty applies.

Two common ways to avoid quarterly vouchers entirely: if you also have a W-2 job, you can increase withholding on Form W-4 to cover the self-employment shortfall, since withholding counts as timely no matter when it happens. And if you had no tax liability in the prior year and were a US citizen or resident for the whole 12-month year, you are exempt from the estimated-tax penalty for the current year. High-income filers should still watch the 110% prior-year rule, and anyone crossing $200,000 in wages plus SE earnings ($250,000 MFJ) should add the 0.9% Additional Medicare Tax to their projection.

Frequently asked questions