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Estimated Tax Penalty Calculator and Safe-Harbor Planner

By Forrest Baumhover, CFP®, EA · Last verified October 30, 2026

Enter your tax, your withholding and your payments. See the penalty for each due date, and what you can still pay to lower it.

This page estimates the IRS penalty for paying too little tax during the year, called the underpayment of estimated tax penalty. It is for people who file Form 1040 for a calendar year. It shows the penalty for each of the four due dates, and the smallest payments that would avoid it.

Step 1: The year

The year sets the four due dates and the rates. This calculator covers 2022 and later.

Step 2: Does any of this fit you?

Check any that fit. Most people check none.

Step 3: This year’s tax

Use your total tax minus your refundable credits. On Form 2210 that is lines 1, 2 and 3 combined, which appears on line 4. This is not your balance due. The calculator takes 90% of this amount. If your tax minus your withholding is under $1,000, you owe no penalty. If this amount comes to less than zero, enter 0.

This is the tax taken out of your pay, pension or other income, plus any excess Social Security tax. On a 2025 Form 1040 it starts on line 25d. Do not count estimated payments here. Leave it blank if you had none.

When should the calculator count your withholding?

The law counts withholding in four equal parts unless you show the actual dates for all of it. Actual dates can raise or lower the result. To use them on your return, you check box D on Form 2210, figure the penalty yourself and attach the form.

Step 4: Last year’s return

Did you file a return for last year?

A no means the calculator can use only this year’s tax to set what you had to pay.

Did last year cover a full 12 months?

A no means the calculator cannot use last year’s tax. If you did not file last year, answer as if you had.

Did you have no tax liability last year?

You had no tax liability if your total tax was zero or you did not have to file a return (Pub. 505). A yes can end the penalty, if last year ran 12 months and you were a citizen or resident all year.

Step 5: Your payments

Every estimated tax payment, with its date

Each payment goes to the oldest unpaid due date first, even if you marked it for a later one. The date of each payment decides how long the penalty runs.

  • Include an overpayment from last year that you applied to this year. Generally date it April 15.
  • For a mailed payment, use the U.S. postmark date. Pub. 505 warns that the postmark may show the day a postal facility processed it, which may differ from the day you mailed it.
  • Tax you pay with your return counts too. Date it the day you file or April 15, whichever comes first.
  • Do not list withholding here.
Did you, or will you, file this return and pay the whole balance by February 2, 2026?

A yes clears the penalty for the fourth due date only. The first three due dates keep theirs. List the payment you send with that return above.

What Catches People Out

  • Timing counts, not just the total. The IRS figures the penalty for each due date on its own. You can owe it for April even if you caught up by January, and even if you get a refund. (Instructions for Form 2210, 2025)
  • Last year’s tax gives you a target you can know in advance. Pay one-fourth of that amount by each due date and you owe no penalty, however much your tax grows this year, if last year’s return covered 12 months. High earners use 110% of last year’s tax. (IRC 6654(d)(1))
  • Withholding gets a head start that estimated payments do not. The law counts it in four equal parts across the year, so extra tax withheld from a December paycheck reaches back to April. A January estimated payment does not. (IRC 6654(g)(1))

How This Calculator Reads the Rules

  • Withheld tax counts as a payment on the date the law assigns it: one of the four due dates, or the actual date if you choose that. So it can stop the penalty on an earlier shortfall. (IRC 6654(g)(1)) The 2025 penalty worksheet, at line 1b, tells filers not to enter withheld tax. A hand computation on that worksheet can come out higher than this estimate.
  • If a due date lands on a Saturday, Sunday or legal holiday, you can pay on the next business day and still pay on time. The calculator counts that payment as made on the printed due date, even when it goes toward an earlier shortfall. (IRC 7503; 2025 instructions, line 11 note)
  • The penalty clock starts on the printed due date, even when that date falls on a weekend. If you pay after the moved date, your days count from the printed date. The 2025 form prints 6/15/25, a Sunday, and its worksheet counts from there. (IRC 6654(b)(2))
  • Each payment goes to the oldest unpaid due date first, even if you marked it for a later one. (IRC 6654(b)(3))
  • The penalty on a shortfall stops on the day you pay it, or on April 15 after the tax year ends, whichever comes first. (IRC 6654(b)(2))
  • The penalty works like simple interest, with no compounding. (IRC 6622(b))
  • The calculator leaves out the first day and counts the last day. It divides by the days in that calendar year: 366 for 2024, 365 otherwise. (2025 Table 4-1; 2024 penalty worksheet)
  • The first-quarter rate runs through April 15. (IRC 6621(b)(2)(B))
  • The calculator rounds to the cent for each payment in each rate period, then adds. (2022 instructions, Example 5)

What This Page Does Not Cover

  • The annualized income method. It may reduce the penalty if your income came unevenly. This calculator does not compute it.
  • Farmers and fishers, nonresident aliens who had no U.S. wage withholding, estates and trusts.
  • Tax years that do not run January through December, or that ran less than 12 months.
  • Deadlines the IRS postponed after a federally declared disaster.
  • The section 965 exclusion and the section 1062 relief for certain farmland sales.
  • Tax years before 2022.
  • The amount of any waiver. Only the IRS decides that.
  • Interest on the penalty, and state penalties.

If one of these fits you, other than a disaster postponement, start with the About Form 2210 page.

Common Questions

Do I have to figure this penalty myself?

Usually not. If you leave the penalty line on your return blank, the IRS figures the penalty and sends a bill. You must file Form 2210 in a few cases, such as when you ask for a waiver, use the annualized method or use actual withholding dates. The About Form 2210 page links the current form. (Instructions for Form 2210, 2025)

Why do I owe a penalty when I am getting a refund?

The penalty looks at what you had paid by each due date, not at where you ended the year. A refund shows you paid enough by the end. It does not show you paid enough by April, June and September. (Instructions for Form 2210, 2025)

Can the IRS remove this penalty?

Sometimes. The IRS can waive it for a casualty, a disaster or another unusual event. It can also waive it if you retired after reaching age 62 or became disabled and had a reasonable cause. The IRS page says reasonable cause alone generally does not work for this penalty. (IRC 6654(e)(3); IRS underpayment penalty page)

My IRS bill shows a different number. Which one counts?

The IRS bill counts. This page gives an estimate from the numbers you enter. Compare your entries with your return and with the payments the IRS shows on your account. Your bill may also add interest, and this page leaves interest out.

This page gives general information about IRS rules, not personalized tax advice. Reading it does not create a practitioner-client relationship. It gives an estimate. The IRS computes the official figure, and your IRS notice or account transcript controls.

This tool asks for dollar amounts, dates and multiple-choice answers only. It never asks for a taxpayer identification number, name or address. The code on this page does not send your answers anywhere.

The Desk checked this tool against IRC 6654, 6621, 6622 and 7503, Treas. Reg. 1.6654-1 and 1.6654-2, and the 2025 Form 2210 and its instructions on October 30, 2026.

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Need help with your specific situation?

This tool gives you the numbers and the citation, but every case has details a calculator can’t weigh. For a second opinion from a tax professional, email Forrest directly. Do not email Social Security numbers, account numbers, or other sensitive information. An email creates no client-practitioner engagement; case-specific advice starts only after both parties have mutually accepted terms and payment has been made.

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Sources

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This page provides general information about IRS procedures. It is not personalized tax advice, and reading it does not create a practitioner-client relationship with Forrest Baumhover, Fbaum Enterprises LLC, or The Federal Tax Desk. Every situation is different — if real money or a real deadline is on the line, consider having a licensed CPA, EA, or tax attorney review your specific facts before you act.

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