IRS Penalty and Interest Calculator (Late Filing and Payment)

If you filed late, paid late, or both, the IRS adds penalties and interest to what you owe. This calculator estimates those charges using the rules the IRS publishes, so you can plan ahead or check a bill. It can't see your IRS account, so treat the result as a starting point.

How to use the calculator

Enter five things:

• Unpaid tax. The tax still owed after withholding, estimated payments and refundable credits. Do not include penalties or interest you were already charged.
• Return due date. For most 2024 individual returns this was April 15, 2025. For 2025 returns it was April 15, 2026.
• Extension filed. Choose "yes" if you filed Form 4868 (or your business filed Form 7004) on time. An extension gives you more time to file, but not more time to pay.
• Date the return was filed. Or choose "not filed yet." In that case the tool counts late-filing months up to your payment date.
• Date the tax is (or will be) paid in full. Use a future date to see what waiting would cost.

The calculator shows each penalty, the interest, and a total.

How the math works

Failure-to-file penalty

The IRS charges 5% of the unpaid tax for each month or part of a month the return is late, up to 25%. "Part of a month" counts as a full month. Filing one day late costs a full 5%.

If the late-payment penalty also applies in the same month, the late-filing penalty is reduced by that amount. So you pay 4.5% for filing late plus 0.5% for paying late, not 5.5%. The late-filing penalty maxes out after five months.

Minimum penalty. If the return is more than 60 days late, the penalty is at least a set dollar amount or 100% of the unpaid tax, whichever is less. That amount depends on when the return was due (not counting extensions), according to the IRS:

Failure-to-pay penalty

The IRS charges 0.5% of the unpaid tax for each month or part of a month it stays unpaid, up to 25%. The rate drops to 0.25% a month while you have an approved payment plan, but only if you filed on time. It rises to 1% a month if you still haven't paid 10 days after the IRS sends a notice of intent to levy (a warning that it plans to seize wages, bank funds or other property).

Interest

Interest runs on unpaid tax from the original due date until you pay, even if you had an extension. It compounds daily. That means each day's interest is added to the balance, and the next day's interest is figured on the larger amount. The IRS also charges interest on the failure-to-file penalty, starting from the return due date (or the extended due date if you had an extension).

The rate is the federal short-term rate plus 3 percentage points, reset every quarter. Recent rates for individual underpayments:

The IRS has not yet announced the rate for January–March 2027. It usually does so in November.

Worked example (the default inputs)

Filing on time, even without paying, would have avoided the $1,125 penalty and its $121 of interest.

Limitations

• Estimate only. The IRS figures penalties from the dates it posts to your account. Small differences in dates or payments change the result.
• Partial payments. The calculator assumes one payment in full. If you paid some along the way, your real penalties and interest will be lower.
• Interest on the late-payment penalty. The IRS starts charging interest on this penalty from the date of a notice, not the due date. The tool leaves it out, so real totals can be slightly higher.
• Higher levy rate and payment-plan rate. The default math uses 0.5% a month. If you got a levy notice or set up a plan, your real rate may differ.
• Penalty relief. You may qualify for relief for reasonable cause, such as a serious illness or a disaster. For 2025 tax year returns and later, the IRS's new Automatic Exemption from Penalty skips late-filing and late-payment penalties for people with three prior years of on-time filing and payment. Interest still applies. See our penalty relief guide.
• Other penalties. The tool does not include the estimated tax penalty, accuracy-related penalties or fraud penalties.

What to do with your result

If you can't pay it all at once, file any missing returns first, then see IRS payment plans and the payment plan calculator. If you have a bill such as a CP14, compare it with this estimate. See also IRS interest, unfiled tax returns and if you can't pay.

IRSV.com is an independent guide and is not affiliated with the IRS. This page is general information, not tax or legal advice. Rules change; confirm details on IRS.gov or with a tax professional. Found an error? Tell us.