About the IRS Penalty Calculator
This IRS penalty calculator estimates what you will owe on top of your tax if you file or pay late. Enter the unpaid tax, the original due date, whether you had a filing extension, the date you filed and the date you paid. It applies the failure-to-file penalty (5% of unpaid tax per month or part of a month, up to 25%), the failure-to-pay penalty (0.5% per month, up to 25%), the minimum penalty for returns more than 60 days late ($525 for returns due in 2026, $535 for 2026 returns due in 2027), and daily-compounded interest at the IRS underpayment rate for each quarter.
When both penalties apply in the same month, the IRS reduces the failure-to-file penalty by the failure-to-pay amount, so the combined charge is 5% for each of the first five months. The calculator models that offset. You can also add the estimated tax underpayment penalty (Form 2210) for quarterly payments that were short, which is charged like interest on each shortfall for the days it was outstanding.
Use it to decide whether to file now even if you cannot pay (filing on time avoids the much larger failure-to-file penalty), or to check an IRS notice. The underpayment interest rate is the federal short-term rate plus 3 points and is reset each quarter; the calculator has the rates the IRS has published from 2022 through the fourth quarter of 2026 (7%, after 6% in the second quarter of 2026) and reuses the latest rate for later dates, or you can enter your own. Assumptions: the tax is paid in one payment, no payment plan or levy notice changes the failure-to-pay rate, and interest the IRS charges on the penalties themselves is not included.
With the default inputs, the total penalties and interest is $1,102.67. Change any value above to recalculate instantly.
How to use the irs penalty calculator
- 1Enter the tax still unpaid on your return.
- 2Enter the original due date, tick the box if you had a filing extension, and enter the dates you filed and paid.
- 3Keep the built-in IRS quarterly interest rates, or switch them off to enter your own rate.
- 4Optionally add any estimated tax shortfall and how many days it was outstanding.
- 5Review each penalty and the total you need to pay.
Formula and method
The failure-to-file penalty is 5% of the unpaid tax for each month or part of a month the return is late (counted from the extended due date if you had an extension), capped at 25%. In any month when the failure-to-pay penalty also applies, the filing penalty is reduced by 0.5%, so it is 4.5% plus 0.5%. If the return is more than 60 days late, the filing penalty is at least the smaller of the annual minimum ($485 for returns due in 2024, $510 in 2025, $525 in 2026 and $535 in 2027; earlier years are treated as $485) or 100% of the tax owed.
The failure-to-pay penalty is 0.5% of unpaid tax per month or part of a month from the original due date, up to 25% — an extension to file does not extend the time to pay. Interest runs from the original due date to the payment date, compounded daily at the IRS underpayment rate for each calendar quarter (dates after Q4 2026 reuse the last published rate). The estimated tax penalty is approximated as shortfall × rate × days ÷ 365 using the rate in effect on the due date. The calculator assumes the tax is paid in a single payment and ignores interest on penalties.
- FTF
- Failure-to-file penalty (IRC §6651(a)(1))
- FTP
- Failure-to-pay penalty (IRC §6651(a)(2))
- r
- IRS underpayment interest rate for each quarter (federal short-term rate + 3%)
Worked examples
$5,000 owed, filed and paid August 10
The return is four months (or part) late. The filing penalty is 4 × 4.5% = 18% ($900) and the payment penalty 4 × 0.5% = 2% ($100). Interest compounds daily at 6% for the 77 days to June 30 and 7% for the 40 days in July and August, adding about $103, for roughly $1,103 in total.
Filed on time, paid 8 months late
Filing on time avoids the filing penalty entirely. Paying on December 1 means 8 months or part months late, so the payment penalty is 8 × 0.5% = 4% of $10,000 = $400. Interest at the quarterly rates (6%, then 7%) adds about $429.
Small balance filed 90 days late
Three months of the combined penalty would be only $54, but because the return is more than 60 days late the minimum applies: the lesser of $525 (returns due in 2026) or 100% of the $400 tax, so the filing penalty equals the full $400. Interest is switched off here to isolate the penalties.
Extension filed, return sent December 20
The extension moves the filing deadline to October 15, so the return is 3 months (or part) late: 3 × 4.5% = $1,080. The payment deadline stayed April 15, so the payment penalty covers 9 months: 9 × 0.5% = $360, and interest from April 15 adds about $374.
Frequently asked questions
What is the IRS penalty for filing late?+
The failure-to-file penalty is 5% of the unpaid tax for each month or part of a month the return is late, up to 25%. If you file more than 60 days late there is also a minimum penalty — the lesser of an inflation-adjusted amount or 100% of the tax owed.
Is there a penalty for filing late if I get a refund?+
No. The penalties are percentages of unpaid tax, so if you are owed a refund there is no failure-to-file penalty. You must still file within three years to claim the refund.
Should I file even if I cannot pay?+
Yes. The failure-to-file penalty is ten times larger than the failure-to-pay penalty. File on time, pay what you can, and apply for a payment plan, which cuts the failure-to-pay rate to 0.25% a month.
Can IRS penalties be waived?+
Often. First-time abatement removes filing and payment penalties if you had no penalties in the previous three years and are otherwise compliant. Reasonable-cause relief is available for events such as serious illness or disasters. Interest is generally not waived.
How is the estimated tax underpayment penalty calculated?+
It is figured on Form 2210 like interest: each quarterly shortfall × the underpayment rate × the days until paid. You usually avoid it if you paid at least 90% of this year’s tax or 100% of last year’s (110% if AGI was over $150,000).
Tax results are estimates based on published rules and simplified assumptions. They are not tax advice — check official guidance or a tax professional for your situation.