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Estimated Tax Safe Harbor Calculator (2026 Form 1040-ES)

Find the smallest 2026 estimated tax payments that avoid the IRS underpayment penalty: 90% of this year or 100%/110% of last year, split by due date.

Tool inputs stay in your browser · optional AI search sends your query

Good to know: Scope: the federal “safe harbor” for 2026 estimated tax from the IRS 2026 Form 1040-ES package: the required annual payment is the smaller of 90% of the tax you expect for 2026 or 100% of the tax on your 2025 return (110% if your 2025 adjusted gross income was more than $150,000, or more than $75,000 if your 2026 filing status is married filing separately). Farmers and fishermen use 66⅔% instead of 90% and do not use the 110% rule. If your 2026 tax minus withholding is under $1,000, you generally do not have to pay estimated tax. Without a full-year 2025 return, only the 90% rule is used. Payments are split into four equal parts due April 15, June 15 and September 15, 2026 and January 15, 2027. Not included: figuring your 2026 tax itself (enter your own estimate), state estimated tax, the annualized income installment method for uneven income, the penalty amount (Form 2210), fiscal-year filers, and 2027 rules. Everything stays in this browser tab; nothing is sent or saved. Independent ToolsKo estimate, not tax advice. Sources reviewed November 12, 2026.

How to use it (step by step)

  1. 1Pick your 2026 filing status, then type the total federal tax you expect for 2026 (after credits). A rough figure is fine.
  2. 2Type the tax from your 2025 return (Form 1040, line 24, minus refundable credits) and your 2025 AGI (line 11). Leave the 2025 tax empty if you did not file a full-year 2025 return.
  3. 3Add the federal income tax withheld from your pay for 2026 and any estimated payments already made. Read the safe harbor amount, the payment for each due date and what is left to pay.

Words to know

Estimated tax
Money you send the IRS during the year on income that has no (or not enough) tax withheld, such as self-employment, rental, interest or investment income.
Safe harbor
A minimum you can pay on time to avoid the underpayment penalty, even if you still owe more tax when you file.
Required annual payment
The smaller of 90% of this year’s tax or 100% (110% for higher incomes) of last year’s tax. Withholding plus estimated payments should reach it.
Underpayment penalty
An extra charge from the IRS, figured on Form 2210, when you paid too little tax by a due date.

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Sources & methods

References checked November 11, 2026. Read each tool’s scope and assumptions before relying on its result.

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