Failure to File vs Failure to Pay: Which IRS Penalty Hurts More

One penalty is ten times the other. Knowing which is which decides your first move when you cannot do everything by April 15.

The two penalties side by side

The failure-to-file penalty (Section 6651(a)(1)) punishes not sending the return: 5 percent of the unpaid tax for each month or part of a month the return is late, maxing out at 25 percent after five months. The failure-to-pay penalty (Section 6651(a)(2)) punishes not sending the money: 0.5 percent per month, also maxing at 25 percent, which takes 50 months. Same cap, wildly different speed.

The file penalty has a floor the pay penalty lacks. File more than 60 days late and you owe at least the lesser of $525 or 100 percent of the unpaid tax for returns due in 2026. Owe $300 and file in December with no extension and the minimum makes your penalty $300, the whole tax. Owe $5,000 and the minimum guarantees at least $525 no matter what the monthly math says.

The combined-month rule

When both penalties apply to the same month, the IRS reduces the file penalty by the pay penalty so the combined charge is 5 percent, not 5.5 percent: 4.5 percent for filing plus 0.5 percent for paying. After five months the file penalty hits its 25 percent ceiling and drops out, leaving the 0.5 percent pay penalty to continue alone toward its own 25 percent cap. The theoretical combined maximum is 47.5 percent of the unpaid tax, reached only after years of nonpayment.

Why filing first always wins

Compare two taxpayers who each owe $5,000 and pay six months late. One files on time: penalty $150 (6 months at 0.5 percent) plus interest. The other files three months late: penalty $750 for filing plus $150 for paying, plus interest. The only difference is a piece of paper, and it costs $750. Filing is free, and an extension to October 15 is free too via Form 4868.

The extension stops the file penalty but not the pay penalty or interest. The IRS is explicit: it is an extension of time to file, not to pay. Pay what you can by April 15 even with the extension; every dollar paid by the deadline avoids both the 0.5 percent penalty and interest on that dollar.

The installment agreement discount

Once an installment agreement under Section 6159 is in effect, the pay penalty drops from 0.5 to 0.25 percent per month, but only for taxpayers who filed on time (including extensions). File late and the discount is unavailable for that year. A short-term payment plan (180 days or less) has no setup fee; a long-term online agreement with direct debit costs $22. Either beats letting 0.5 percent compound monthly.

Interest: the third charge

Interest accrues on the unpaid tax from the original due date until paid in full, at the federal short-term rate plus 3 percentage points, compounded daily and reset quarterly. For the quarter beginning July 1, 2026 the rate is 7 percent. Interest also accrues on the penalties themselves once assessed. Unlike penalties, interest cannot be abated for reasonable cause; it stops only when the balance is paid or the underlying penalty is removed.

Sources: IRS Topic No. 653 (penalties); IRS interest rate announcements (Rev. Rul. 2026-10). Data current as of October 2026. Not tax advice.

Frequently asked questions

Which is worse: failure to file or failure to pay?

Failure to file, by far: 5% per month versus 0.5% per month. Always file on time even if you cannot pay the balance.

What is the minimum late-filing penalty?

For returns due in 2026, if you file more than 60 days late the minimum is the lesser of $525 or 100% of the unpaid tax.

Do the penalties stack in the same month?

No. The combined charge is capped at 5% per month (4.5% filing + 0.5% paying) until the file penalty maxes out at 25%.

Does a tax extension stop penalties?

It stops the failure-to-file penalty only. The failure-to-pay penalty and interest continue from the April deadline on any unpaid balance.

How do I cut the failure-to-pay penalty in half?

Get an approved installment agreement and file on time; the pay penalty drops to 0.25% per month while the agreement is in effect.