The fee for filing taxes late is 5% of your unpaid tax for each month or partial month your return is overdue, up to 25% of the balance, and that charge runs alongside a separate 0.5% monthly penalty for not paying and daily interest at an annual rate that currently sits at 7%. If you’re owed a refund, there’s no penalty at all. If you owe even a small amount, the combined cost climbs quickly, and after 60 days a minimum penalty kicks in regardless of how little you owe.
The 5% Monthly Failure to File Penalty
The main charge for a late return is the failure-to-file penalty: 5% of your unpaid tax for each month, or partial month, the return is late, capped at 25% of what you owe.1Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax The cap hits at five months, so a return that sits unfiled from April through September has already generated the full 25%.
“Partial month” is literal. One day into a new month counts as a whole month. Someone who files six days late pays the same 5% for that month as someone who files 29 days late, so if you’re already behind, getting the return in before the calendar flips can save you a full percentage tier.
The penalty is calculated on unpaid tax. If your withholding and credits already cover your liability, the 5% is applied to zero and you owe nothing in penalties for the late filing itself.1Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax
The Minimum Penalty After 60 Days
Once a return is more than 60 days late, the IRS applies a minimum penalty no matter how small the balance. For returns due in 2026, that minimum is the lesser of $525 or 100% of the tax owed.2Internal Revenue Service. Failure to File Penalty The dollar figure is adjusted annually for inflation.3Internal Revenue Service. Rev Proc 2024-40
The “lesser of” language changes the math at both ends. Owe $200 and file four months late, and the ordinary calculation gives $40; because you’re past 60 days, the minimum takes over at $200, which is 100% of the tax and still less than $525. Owe $2,000 and file 90 days late, and the ordinary calculation gives $300, but the $525 floor applies because it’s less than 100% of what you owe. The point is that a small balance won’t rescue you from a meaningful penalty once you’ve crossed the two-month line.
The 0.5% Failure to Pay Penalty
Separate from the filing penalty, the IRS charges 0.5% of the unpaid balance for every month the tax itself goes unpaid, up to a 25% ceiling. This one starts the day after the deadline and runs even when you filed the return on time but skipped the payment.1Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax
At half a percent a month, the 25% cap takes 50 months to reach, so this charge grinds slowly compared with the filing penalty. It still compounds with interest the whole way.4Internal Revenue Service. Failure to Pay Penalty
There’s a discount. If you filed on time, including any extension, and then set up an IRS installment agreement, the rate drops to 0.25% per month. The statute requires the return to have been filed by the due date (extensions count) for the reduced rate to apply, so filing late and then requesting a payment plan doesn’t qualify.1Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax
How the Two Penalties Combine
When both penalties apply in the same month, the IRS doesn’t simply stack 5% and 0.5%. The failure-to-file portion is reduced by the failure-to-pay amount, so you pay 4.5% for not filing and 0.5% for not paying: 5% combined per month.2Internal Revenue Service. Failure to File Penalty
After five months, the failure-to-file penalty hits its 25% cap and stops. The 0.5% payment penalty keeps running on its own until it reaches its own 25% cap. The theoretical maximum across both is 50% of the tax owed. Interest is separate, and it doesn’t stop.
Interest on the Unpaid Balance
Interest starts the day after the deadline and runs on whatever tax is still unpaid. The rate is the federal short-term rate plus three percentage points, recalculated quarterly. For the second quarter of 2026, the individual underpayment rate is 7%.5Internal Revenue Service. Quarterly Interest Rates
Interest compounds daily and has no ceiling. Once penalties are assessed, interest runs on those too, so the pot grows on itself until you pay everything off.6Office of the Law Revision Counsel. 26 USC 6621 – Determination of Rate of Interest
If you can’t pay in full, filing anyway is the single biggest lever you have. It kills the 5%-a-month filing penalty and leaves only the 0.5% payment penalty and interest, which cuts your monthly cost by roughly 90%.
An Extension Stops the Filing Penalty, Not the Payment One
Form 4868 gives you an automatic six-month extension to submit your return, pushing the deadline from April 15 to October 15. As long as you file by the extended date, the failure-to-file penalty goes away entirely.7Internal Revenue Service. Application for Automatic Extension of Time to File US Individual Income Tax Return
What the extension doesn’t do is give you extra time to pay. The tax itself is still due April 15. File Form 4868 without a payment, and the 0.5% monthly penalty and daily interest start running the next day on whatever you owe.8Internal Revenue Service. When to File This trips up a lot of people who assume the extension moves everything.
If you’re unsure of the exact number, estimate what you owe and send a payment with Form 4868. Anything you pay in April reduces the base the penalties and interest are calculated on. Overpay and the difference comes back as a refund when the return is filed.
No Fee If You’re Owed a Refund
If the IRS owes you money, filing late costs you nothing in penalties. Both charges are percentages of unpaid tax, and there’s no unpaid tax to apply them to.
The real risk is losing the refund. You have three years from the original filing deadline to claim it; after that, the money stays with the U.S. Treasury.9Office of the Law Revision Counsel. 26 USC 6511 – Limitations on Credit or Refund For a 2025 return due April 15, 2026, that cutoff is April 15, 2029. The IRS doesn’t send reminders about unclaimed refunds.
Getting the Penalty Reduced or Removed
Two forms of relief cover most late filers, and both are underused.
First Time Abate
If you’ve filed on time and stayed penalty-free for the three tax years before the year at issue, the IRS will generally waive a failure-to-file or failure-to-pay penalty on request. You need all required returns filed for those prior three years and no penalties during that period, other than penalties removed for a reason unrelated to this same program.10Internal Revenue Service. Administrative Penalty Relief
You can request it by calling the number on the IRS notice you received. No documentation is required to start. If you’d rather write, Form 843 or a plain letter works.10Internal Revenue Service. Administrative Penalty Relief
Reasonable Cause
If you don’t qualify for First Time Abate, you can still ask for relief by showing “reasonable cause.” The IRS looks at whether you used ordinary care and were still unable to file or pay on time.11Internal Revenue Service. Penalty Relief for Reasonable Cause
Reasons that tend to work include natural disasters, serious illness, a death in the immediate family, an inability to obtain records, and IRS system errors that blocked electronic filing. Reasons that generally don’t: not knowing the deadline, making a mistake on the return, or not having the money. The IRS says lack of funds by itself isn’t reasonable cause, though it can be weighed alongside other factors.11Internal Revenue Service. Penalty Relief for Reasonable Cause
When Non-Filing Becomes Fraud or a Crime
Everything above is civil. If the IRS proves your failure to file was fraudulent rather than negligent, the monthly rate triples from 5% to 15% and the cap climbs from 25% to 75% of unpaid tax.1Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax The IRS carries the burden of proving fraud, so this doesn’t apply to someone who just forgot or put it off.
At the far end, willfully refusing to file is a federal misdemeanor carrying a fine of up to $25,000 and up to one year in prison for each year of non-compliance.12Office of the Law Revision Counsel. 26 USC 7203 – Willful Failure to File Return, Supply Information, or Pay Tax Criminal prosecution is rare and generally targets people who owed substantial amounts and deliberately ignored repeated IRS notices over several years. A return that’s a few weeks late is a civil matter.