How the payments are worked out
2026 tax = SE tax + income tax + Additional Medicare Tax
Required for the year = smaller of 90% × 2026 tax or 100% × 2025 tax (110% if 2025 AGI was over $150,000, or $75,000 married filing separately)
Each payment = (required − withholding) ÷ 4
Required for the year = smaller of 90% × 2026 tax or 100% × 2025 tax (110% if 2025 AGI was over $150,000, or $75,000 married filing separately)
Each payment = (required − withholding) ÷ 4
- SE tax: 15.3% on 92.35% of your profit, with Social Security capped at $184,500 including W-2 wages.
- Income tax: wages + other income + profit − half of SE tax = AGI. Subtract the 2026 standard deduction and, if you choose, the 20% qualified business income (QBI) deduction, then apply the 2026 brackets.
- Safe harbor: you avoid the underpayment penalty if withholding plus estimated payments, paid on time, reach the smaller of the two amounts above.
- Under $1,000: if you expect to owe less than $1,000 after withholding and refundable credits, you don't have to make estimated payments.
2026 due dates
| Payment | For income earned | Due |
|---|---|---|
| 1 | January 1 – March 31 | April 15, 2026 |
| 2 | April 1 – May 31 | June 15, 2026 |
| 3 | June 1 – August 31 | September 15, 2026 |
| 4 | September 1 – December 31 | January 15, 2027 |
You don't need the January payment if you file your 2026 return and pay everything by February 1, 2027. Farmers and fishers have their own rules.
Worked example
A single freelancer expects an $80,000 profit, has no withholding, and paid $9,000 in total tax for 2025 on a $70,000 AGI.
- SE tax: 15.3% × $73,880 = $11,303.64. Half, $5,651.82, is deductible, so AGI is $74,348.18.
- Taxable income before QBI: $74,348.18 − $16,100 = $58,248.18. QBI deduction: 20% × ($80,000 − $5,651.82) = $14,869.64, limited to 20% of $58,248.18 = $11,649.64.
- Income tax on $46,598.54 is $5,343.83, so the 2026 total is $16,647.47.
- Required: the smaller of 90% × $16,647.47 = $14,982.72 or 100% × $9,000. That's $9,000, or $2,250 a quarter. The other $7,647.47 is due in April 2027, with no penalty.
Limits of this estimate
- Withholding is treated as paid evenly through the year, as the IRS does unless you elect otherwise. Equal payments are assumed; uneven income can use the annualized method in Publication 505 (Form 2210 Schedule AI).
- The QBI deduction is included only when taxable income is at or below the 2026 threshold ($201,750; $403,500 joint; $201,775 separate). Above it, wage and property limits and service-business rules apply, so it's left out. QBI here is profit minus half of SE tax; self-employed health insurance and retirement contributions aren't subtracted.
- Only the standard deduction is used. Credits (child tax credit and others), capital gains rates, the net investment income tax, AMT and state tax aren't included. Use the income tax calculator for credits.
- The prior-year safe harbor needs a 2025 return covering all 12 months.
Sources
- 2026 Form 1040-ES – 2026 due dates, 90%/100%/110% rules, $1,000 rule, SE worksheet
- IRS Publication 505 – estimated tax and the underpayment penalty
- IRS Rev. Proc. 2025-32 – 2026 brackets, standard deduction, §199A thresholds
- 26 U.S.C. 199A (qualified business income deduction) – 20% deduction and the $400 minimum for active QBI of $1,000 or more (from 2026)
- SSA contribution and benefit base – $184,500
- IRS Topic 560, Additional Medicare Tax – Additional Medicare Tax