2026 planning - IRS estimated tax safe-harbor rules

Quarterly Estimated Tax Calculator

Estimate 2026 federal estimated tax payments using the 90% current-year rule and prior-year safe-harbor rules.

Reviewed QuickTaxTools editorial review Updated April 25, 2026 and aligned to the sources linked below.
Tax year 2026 This page uses the federal or state scope called out in the methodology section.
Source set IRS, SSA, and official guidance Primary references are linked on-page and collected in the site sources library.
Methodology Source library
Current-year and prior-year inputs
Enter your best current-year tax estimate before estimated payments.
Use total tax from your prior-year Form 1040.
Estimated payment plan
Enter your numbers to estimate the remaining quarterly payment plan.
Required annual payment
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Estimated tax needed
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Remaining due
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Per remaining quarter
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90% of expected current-year tax-
Prior-year safe harbor-
Safe-harbor factor used-
Expected withholding-
Payments already made-
Next estimated tax due date-
Sources: IRS Publication 505, IRS Form 1040-ES instructions, and IRS estimated tax safe-harbor rules. This calculator uses the 90% current-year rule and the 100% or 110% prior-year safe-harbor method.
Estimate only. Farmers, fishermen, annualized-income method users, and taxpayers with uneven income should use the detailed IRS worksheets instead.

How this estimate helps

This page is best for people with self-employment, freelance, investment, or side income not fully covered by withholding. It shows the minimum annual payment target and then spreads the remaining amount across the quarters you still have left in the year.

Methodology

How this calculator works

  • Compare 90% of expected current-year tax with the applicable prior-year safe-harbor target.
  • Reduce the annual requirement by federal withholding because withholding counts as paid throughout the year.
  • Spread the remaining balance over the quarter count selected on the page for planning purposes.
Worked example

Example scenario

Someone with contract income can use this calculator after updating their annual tax estimate. The tool compares the current-year and prior-year safe-harbor methods, subtracts withholding and estimated payments already made, and then shows the amount left for the remaining quarters.

Primary references

Direct sources for this page

IRS Publication 505

Safe-harbor rules and estimated tax planning.

About Form 1040-ES

Estimated tax payment guidance and due dates.

IRS When to file

Federal calendar-year filing and timing context.

Reviewed with the site-wide editorial methodology and the full sources library.
Next step

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Investments And Digital Assets
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Last updated: April 25, 2026. All calculator pages in this directory use the same static HTML/CSS/JS design and are linked together for Netlify deployment.
Frequently asked questions
What safe-harbor rule does this calculator use?
It compares 90% of your expected current-year tax with 100% of your prior-year tax, or 110% when prior-year AGI is above the IRS threshold used for safe-harbor payments.
Do withholding payments reduce estimated tax requirements?
Yes. Federal withholding is treated as paid throughout the year, so it reduces the amount that still needs to be covered by estimated tax payments.
Does this replace Form 1040-ES worksheets?
No. This is a planning calculator. The official IRS worksheets in Publication 505 and Form 1040-ES should still be used before filing or mailing payments.