The IRS charges two separate penalties when you file after the deadline

The failure-to-file penalty and the failure-to-pay penalty are calculated differently and can both apply to the same return. The failure-to-file penalty is typically larger — it costs 5% of the unpaid tax for each month or part of a month your return is late, up to a maximum of 25%. The failure-to-pay penalty is 0.5% of unpaid tax per month, also capping at 25%. If you owe money when you file late, you pay both penalties plus interest on the unpaid amount.

The penalties start the day after the deadline passes. For most people, that's April 15. If you filed for an extension, the penalties begin after your extension deadline — typically October 15 for individual returns. The IRS calculates penalties based on how much tax you actually owed, not on the total income you reported.

If you filed late but don't owe money — because you're getting a refund — you don't pay a failure-to-file penalty. You also don't pay a failure-to-pay penalty if you don't owe. However, you do lose the opportunity to claim that refund if you wait more than three years from the original deadline to file.

Key Takeaways

  • The failure-to-file penalty is 5% per month of unpaid tax, up to 25% total, and applies whenever you file after April 15 without an extension.
  • The failure-to-pay penalty is 0.5% per month of unpaid tax, also capping at 25%, and runs separately from the filing penalty.
  • Interest accrues on unpaid tax from the original deadline, and the IRS compounds it daily — this cost often exceeds the penalties themselves.
  • If you're owed a refund, you don't pay a filing penalty, but you lose the refund entirely if you don't file within three years.
  • Filing an extension moves your deadline to October 15 and resets when penalties begin, but it does not extend the time to pay what you owe.

How the failure-to-file penalty is calculated

The failure-to-file penalty accrues at 5% of your unpaid tax for each month or partial month you're late. A partial month counts as a full month — if you file one day into a new month, you owe the full 5% for that month. The penalty stops accumulating once it reaches 25% of your unpaid tax, even if you file much later.

Example: You owed $2,000 in tax and filed four months late without an extension. Your penalty is 5% × 4 months × $2,000 = $400. If you filed 11 months late, the penalty would be capped at 25% × $2,000 = $500, not 55%.

The penalty applies only to the tax you actually owed. If you reported $60,000 in income but your actual tax liability was $8,000, the penalty is calculated on the $8,000, not the $60,000. The IRS determines your actual tax liability by reviewing your return after you file it.

How the failure-to-pay penalty works

The failure-to-pay penalty is 0.5% of unpaid tax per month, also capping at 25%. This penalty runs at the same time as the failure-to-file penalty — they don't replace each other. If you file late and owe money, you're charged both penalties simultaneously.

The failure-to-pay penalty continues to accrue as long as you haven't paid the full amount owed. If you file your return six months late and then pay the tax immediately, you owe the failure-to-file penalty for six months (30%) and the failure-to-pay penalty for one month (0.5%), totaling 30.5% in penalties. If you don't pay for a full year after filing, the failure-to-pay penalty alone reaches 6% (0.5% × 12 months).

You can reduce the failure-to-pay penalty by setting up a payment plan with the IRS. Once you're on an approved plan, the penalty drops to 0.25% per month instead of 0.5%. This reduction applies only while you're making payments on schedule.

Interest charges on late-filed returns

Interest is separate from penalties and often costs more. The IRS charges interest on any unpaid tax from the original deadline — April 15 for most returns — regardless of when you file. The interest rate changes quarterly and is set by federal law; it's currently in the range of 8% to 10% annually, compounded daily.

Interest accrues from April 15 until you pay in full. If you file in July and owe $5,000, you owe interest on that $5,000 for the three months from April 15 to July 15, plus the penalties. The longer you wait to pay, the more interest accumulates. Over a year, interest alone can add hundreds of dollars to what you owe.

Unlike penalties, interest cannot be waived or reduced by the IRS except in very narrow circumstances — primarily if the IRS made an error in its own processes that caused a delay.

When you might avoid or reduce penalties

The IRS can waive penalties if you have reasonable cause — a legitimate reason you couldn't file or pay on time. Common reasons include serious illness, death in the family, natural disaster, or reliance on a tax professional who missed the deadline. You must request the waiver by submitting Form 843 (Claim for Refund and Request for Abatement) or by writing to the IRS office that sent you the penalty notice.

The IRS is more likely to grant reasonable cause if this is your first penalty in the past three years and you filed and paid as soon as you could after the problem resolved. If you have a history of late filings, the IRS is less likely to waive the penalty, though it's still worth requesting.

Filing an extension doesn't eliminate penalties if you don't file by the extension deadline. It only moves the deadline from April 15 to October 15. If you file after October 15, penalties begin accruing as if you had missed the original April 15 deadline.

What happens if you file late but don't owe money

If you're owed a refund, you don't pay a failure-to-file penalty or a failure-to-pay penalty. The IRS has no incentive to penalize you for filing late when they owe you money. However, you do lose the refund if you don't file within three years of the original deadline.

Example: Your 2022 return was due April 15, 2023. If you don't file by April 15, 2026, the IRS keeps your refund. You can still file after that date, but you won't receive the money. Filing an extension doesn't extend this three-year window — it only extends the filing deadline itself.

Frequently Asked Questions

Can the IRS charge penalties if I filed an extension?

An extension moves your filing deadline to October 15 but does not extend the time to pay. If you owe tax and don't pay by April 15, the failure-to-pay penalty begins accruing even if you filed an extension. The failure-to-file penalty begins on October 16 if you haven't filed by then.

What's the maximum penalty I could owe?

If you file very late and owe money, the maximum combined penalty is 50% of unpaid tax: 25% for failure to file plus 25% for failure to pay. Interest compounds on top of this. A $5,000 tax debt filed 12 months late could result in $2,500 in penalties plus several hundred dollars in interest.

Do I owe penalties if I file late but the IRS owes me a refund?

No. You don't owe a filing penalty or payment penalty if you're owed money. However, you forfeit the refund if you don't file within three years of the original deadline, so filing late still costs you.

Can I get the penalty removed if this is my first time?

You can request removal by submitting Form 843 and explaining your reason for filing late. The IRS grants reasonable cause more readily to first-time offenders, but approval isn't may provide. You must show the delay was beyond your control, not simply that you forgot or procrastinated.