In Short
You generally avoid the underpayment penalty by paying the smaller of 90% of this year's tax or 100% of last year's tax (110% if last year's AGI was over $150,000, or $75,000 married filing separately), in four equal payments [1][2]. For 2026 they are due April 15, June 15 and September 15, 2026, and January 15, 2027 [2]. A single filer expecting $80,000 of profit, whose 2025 tax was $12,000, can pay $3,000 a quarter.
How to Use the Quarterly Estimated Tax Calculator
- Enter this year's expected business profit and any other income with no tax withheld.
- Enter federal tax withheld this year, if you also have a job.
- Enter last year's total tax and AGI from your Form 1040.
- Or tap Say It All: “I expect 80k in business profit plus other income of 10,000, single, my tax last year was 14,000 on an AGI of 70,000.”
- Download the calendar reminders so each due date lands in your calendar.
The Formula
The required annual payment is the smaller of two safe harbors. Withholding counts toward it, and the rest is split into four equal installments.
- This year's tax = income tax + self-employment tax
- Safe harbor A = 90% × this year's tax
- Safe harbor B = 100% × last year's total tax (110% if last year's AGI > $150,000, or > $75,000 married filing separately)
- Required annual payment = the smaller of A and B
- Each quarterly payment = (required annual payment − withholding) ÷ 4
- No estimates required when you expect to owe under $1,000 after withholding
Worked Examples
| Scenario | Inputs | Result |
|---|---|---|
| Last year's tax is lower than this year's | $80,000 profit, last year's tax $12,000, AGI $70,000 | 2026 tax $16,647 · safe harbor $12,000 (100% of last year) · $3,000 a quarter |
| This year's tax is lower than last year's | $80,000 profit, last year's tax $20,000, AGI $70,000 | Safe harbor $14,983 (90% of this year) · $3,746 a quarter |
| High income: the 110% rule | $200,000 profit, last year's tax $40,000, AGI $180,000 | 2026 tax $53,431 · safe harbor $44,000 (110% of last year) · $11,000 a quarter |
| Withholding covers most of it | $20,000 profit, $3,000 withheld | 2026 tax $3,025 · under $1,000 owed after withholding · no estimates required |
Illustrative examples, not projections. Figures use the tax year shown and the assumptions above.
Who Has to Pay Quarterly Estimated Taxes?
Anyone who expects to owe $1,000 or more when they file, after withholding and credits [1]. That covers most self-employed people, contractors and owners of pass-through businesses, plus people with large investment or rental income and no withholding.
The IRS is a pay-as-you-go system: tax is due as income is earned, not only in April. Paying too little, or too late, adds an underpayment penalty figured like interest on each late installment [4].
What Are the 2026 Estimated Tax Due Dates?
For tax year 2026: April 15, 2026; June 15, 2026; September 15, 2026; and January 15, 2027 [2]. The January payment can be skipped if you file your 2026 return by February 1, 2027 and pay the full balance with it [2].
For tax year 2025 the dates were April 15, June 16 and September 15, 2025, and January 15, 2026 [3]. When a date falls on a weekend or holiday, it moves to the next business day.
How Does the Safe Harbor Work?
The safe harbor is the minimum that keeps the penalty away, even if you owe more when you file. It is the smaller of 90% of this year's tax and 100% of last year's tax, as long as last year was a full 12-month tax year [2][5]. If last year's AGI was above $150,000 ($75,000 married filing separately), the prior-year figure becomes 110% [2].
Using last year's tax is predictable: the number is already on your return. The trade-off is that if your income grew, the rest of this year's tax is still due in April. Income that arrives unevenly may qualify for the annualized installment method on Form 2210, which can lower the early payments [4].
Frequently Asked Questions
How do I calculate quarterly estimated taxes?
Estimate this year's income and self-employment tax, take the smaller of 90% of it or 100% of last year's tax (110% above $150,000 AGI), subtract withholding, and divide by four.
When are 2026 quarterly taxes due?
April 15, 2026, June 15, 2026, September 15, 2026 and January 15, 2027, according to the 2026 Form 1040-ES [2].
What happens if I miss a quarterly estimated tax payment?
The IRS charges an underpayment penalty, figured separately for each late or short installment, like interest on the amount and the days it was late [4]. Paying as soon as possible limits it.
Do I need to pay estimated taxes in my first year of self-employment?
If you expect to owe $1,000 or more after withholding, yes. If you had no tax liability for a full 12-month prior year, you generally owe no penalty for this year [5].
Can I pay all my estimated tax at once?
Yes. You can pay the full year's estimate by the first due date, April 15 [2]. Paying more in a later quarter doesn't cancel a penalty on an earlier quarter that was short.
Sources
- Estimated taxes — Internal Revenue Service
- 2026 Form 1040-ES, Estimated Tax for Individuals — Internal Revenue Service
- 2025 Form 1040-ES, Estimated Tax for Individuals — Internal Revenue Service
- About Form 2210, Underpayment of Estimated Tax by Individuals — Internal Revenue Service
- Publication 505, Tax Withholding and Estimated Tax — Internal Revenue Service
Official sources only: the IRS, SSA, BLS and other government agencies. Read how Zentavos researches.