IRS Late Filing and Payment Penalty Calculator

How IRS penalties and interest add up

Tax you pay late draws two penalties and interest, and each runs on its own clock. The late-payment penalty starts the day after the due date. The late-filing penalty starts the day after your filing deadline, which is October 15 if you got an extension. Interest starts with the tax and runs until you pay.

Both penalties count months, not days, and part of a month counts as a whole one. The IRS's failure-to-pay page puts it this way: "We apply full monthly charges, even if you pay your tax in full before the month ends." So $10,000 paid on May 15, 2026 owes one month, $50, while paid on May 16 it owes two, $100. Each penalty month ends on the due date's day of the month, here the 15th.

IRS penalty and interest formulas

late payment = Σ over the months: tax unpaid at the month's start × 0.5% (0.25% on a payment plan, 1% after a levy notice), at most 25% of T in all
late filing = T × 5% × months late, at most 5 months, − the late-payment penalty of those months
more than 60 days late: late filing ≥ the lesser of the year's minimum ($525 for a 2026 due date) and T
interest on the tax = T × (Π (1 + r ÷ D)^days − 1), from the due date to the day you pay
interest on the late-filing penalty = late filing × (Π (1 + r ÷ D)^days − 1), from the filing deadline
T is the tax unpaid at the due date, r the quarter's yearly rate and D the days in the year: 365, or 366 in a leap year

Worked examples

The IRS's own example. The Internal Revenue Manual, at 20.1.2.3.8.7.1, works a $5,000 return due April 15, 2022 and filed July 13. The taxpayer paid $2,000 on June 1 and the rest with the return. The late-payment penalty is two months on $5,000 and one on $3,000: "$50 + $15 = $65". The late-filing penalty is "$750 - $65 = $685". Enter those dates with Part paid earlier, and this page gives the same $65.00 and $685.00. It adds what the example leaves out: $40.86 of interest on the tax and $6.96 on the penalty.

A small tax 61 days late. The Internal Revenue Manual's example of the minimum penalty has $148 of tax on a 2021 return. The return and the payment arrive on June 15, 2022, 61 days after April 15. The late-payment penalty is 2 × 0.5% × $148 = $1.48. Without the minimum, the late-filing penalty would be $14.80 − $1.48 = $13.32. But the minimum for that return is "the lesser of $435 or the $148 unpaid tax", so it is $148. This page gives $1.48 and $148.00, with $0.99 of interest on each.

An extension, filed five days late. With an extension to October 15, 2026, $10,000 filed and paid on October 20 owes one month of late-filing penalty. That is $450, after that month's $50 of late-payment penalty comes off. The late-payment penalty is $350 for 7 months. Interest is $345.53 on the tax and $0.43 on the late-filing penalty, which began to run only on October 15. The total is $1,145.96, against $695.53 had the return gone in by the deadline.

Assumptions and limits

• The tax unpaid on the due date is your balance due: the tax on your return less withholding, estimated payments and credits. The federal income tax calculator works out that balance.
• Dates are the ones the IRS counts. A late paper return counts from the day the IRS gets it. The Internal Revenue Manual's minimum-penalty example says such a return "is not considered filed until it is received at the IRS office where it is required to be filed."
• You pay what is left of the tax, with the penalties and interest, on one date. That date is on or after the day you file, and one earlier payment can be entered. If you paid all the tax before filing, the penalty bill comes later, and its interest runs until you pay it.
• A due date on a weekend or holiday stays the due date. A return filed or tax paid by the next business day is on time. Later than that, the months, the 60 days and the interest count from the 15th itself. The Internal Revenue Manual says the IRC 7503 rule "does not change the actual respective due date for the purpose of computing penalties or interest if the return or payment is mailed late." Say $1,000 of tax on a 2021 return was due April 15, 2022, and the return could go in by Monday, April 18. Filed and paid on June 17, it is 63 days late, not 60, so the $435 minimum applies.
• With a levy notice, the page adds no interest on the late-payment penalty. That interest starts with your first bill, whose date the page does not ask for. So a notice can show more interest.
• The next business day after a due date skips weekends and the legal holidays of Washington, D.C., which 26 CFR 301.7503-1(b) uses for IRC 7503. They are the federal holidays, the Friday before or the Monday after one that falls on a weekend, Emancipation Day and Inauguration Day. The 10 business days after a bill of $100,000 or more skip the same days. A statewide legal holiday where the return is filed can move the next business day a day later, and the page does not count those. Tax assessed later, fraud and accuracy penalties, and the estimated tax penalty are not included.
• Interest rates are the IRS's for each quarter from January 2017 to December 2026. The rate for January to March 2027 comes out in late November 2026, so later payment dates wait for it.

These figures are estimates for learning and planning, not financial, tax, legal or investment advice. Terms of use.

What to do about an IRS penalty

File now, even if you cannot pay. On the default case, a return filed by May 15 instead of August 20 owes a late-filing penalty of $450 instead of $2,250. If you are not sure you have to file at all, the tax filing requirement calculator checks it.

Pay your CP14 within 21 days of its date if you can. On the default case, paying a notice dated September 28 on October 15 keeps $41.21 of interest off the bill. If you cannot pay it all, set up a payment plan before a CP504 arrives. If you cannot pay at all, the offer in compromise calculator shows what the IRS may accept.

Ask for the penalties to come off. With three clean prior years, a 2025 return's penalties are not charged at all. On the default case that is $2,550 of penalties and the $75.51 of interest on them. For an older year, call the number on your notice and ask for First Time Abate. A refund of a penalty you already paid has a deadline, which the refund claim deadline calculator works out.

Track how long the IRS can collect what is left. The collection statute expiration date calculator counts the 10 years from the assessment date on your notice.

Frequently asked questions