What the IRS charges when you pay taxes late

The IRS charges a failure-to-pay penalty when you submit your tax payment after the deadline, even if you filed your return on time. The penalty is 0.5% of the unpaid tax for each month or part of a month the payment is late. If you owe $5,000 and pay 60 days late, you will owe roughly $50 in penalty alone, plus interest on both the original tax and the penalty itself.

The penalty stops accruing once you pay in full, but interest continues to compound daily until the debt is settled. The IRS also charges interest on the penalty amount, not just the original tax. This means a late payment costs more than the tax itself — sometimes significantly more if the delay stretches into months.

The penalty applies whether you underpaid through withholding, made estimated payments that fell short, or simply did not pay at all. It does not matter if you filed your return on time; the clock starts from the tax deadline, which is typically April 15 for individual returns.

Key Takeaways

  • The IRS charges 0.5% of unpaid tax per month or partial month that payment is late, separate from interest charges.
  • Interest accrues daily on both the original tax and the penalty, compounding until you pay in full.
  • The penalty applies even if you filed your return on time — it is based on when you pay, not when you file.
  • Paying as soon as you discover the debt stops the penalty from growing further, though interest will continue.
  • The IRS may reduce or remove the penalty if you have a reasonable cause, such as a serious illness or death in the family during the tax season.

How the penalty is calculated

The IRS calculates the penalty as a percentage of the tax you did not pay by the deadline. If you owed $10,000 and paid nothing until 90 days after April 15, the penalty would be roughly $150 (0.5% × 3 months × $10,000). The exact amount depends on how many full or partial months passed between the deadline and your payment date.

The penalty maxes out at 25% of the unpaid tax. This means if your payment is more than 50 months late, the penalty stops growing at that ceiling. However, interest continues to accrue on top of the penalty, so the total debt keeps rising.

If you made a partial payment before the deadline and paid the rest late, the penalty applies only to the portion paid late. For example, if you owed $10,000, paid $6,000 by April 15, and paid the remaining $4,000 three months late, the penalty would be calculated on the $4,000, not the full $10,000.

Interest charges on top of the penalty

The IRS charges interest separately from the penalty. The interest rate changes quarterly and is tied to the federal short-term rate plus 3%. For 2024, the rate has been 8% annually for most of the year, though it varies. The IRS publishes the current rate on its website, and it changes on January 1, April 1, July 1, and October 1 each year.

Interest compounds daily, meaning you owe interest on the interest itself. This is why a debt that sits unpaid for a year or more can nearly double. The interest applies to the original tax, the penalty, and any previous interest that has accrued.

Unlike the penalty, interest does not have a maximum cap. It will continue to grow as long as the debt remains unpaid. This is why paying as soon as possible, even if you cannot pay the full amount, reduces the total cost significantly.

When the IRS may waive or reduce the penalty

The IRS can remove the penalty if you show reasonable cause — a legitimate reason you could not pay on time. Common reasons include serious illness or hospitalization during tax season, a death in your immediate family, a natural disaster that destroyed your records, or reliance on a tax professional who made an error.

To request penalty relief, you must file Form 843 (Claim for Refund and Request for Abatement) or write a letter to the IRS explaining your situation. You will need to provide supporting documentation — a hospital record, death certificate, insurance adjuster's report, or a written statement from your tax preparer, depending on your reason.

The IRS also has an automatic relief provision called First Time Penalty Abatement. If you have no penalties in the prior three years and you pay the tax within a certain timeframe after the IRS contacts you, the penalty may be removed automatically. This applies only to the failure-to-pay penalty, not to other penalties like failure-to-file.

The difference between failure-to-pay and failure-to-file penalties

The failure-to-file penalty applies when you do not submit your return by the deadline. It is 5% of unpaid tax per month, up to 25% total — ten times steeper than the failure-to-pay penalty. If you both file late and pay late, the IRS charges both penalties, though the combined penalty cannot exceed 25%.

Filing on time but paying late results in only the failure-to-pay penalty. Filing late but paying on time results in only the failure-to-file penalty. The key distinction is the date you submit your return versus the date you send your payment.

If you cannot file by April 15, requesting an extension (Form 4868) moves your filing deadline to October 15 but does not extend your payment deadline. You still owe payment by April 15 to avoid the failure-to-pay penalty, even if you have not filed yet.

What happens if you cannot pay the full amount

Paying even a partial amount stops the penalty from growing on that portion. If you owe $5,000 and can only pay $2,000 immediately, pay it. The penalty will accrue only on the remaining $3,000, not the full $5,000. Interest will still apply to everything, but reducing the unpaid balance reduces future penalty charges.

The IRS offers payment plans for amounts you cannot pay in full. A short-term extension allows up to 180 days to pay without a formal agreement. A long-term installment agreement lets you pay over months or years, though you will owe a setup fee (usually $31 to $225, depending on how you set it up) and interest continues to accrue on the unpaid balance.

You can set up a payment plan through the IRS website, by phone at 1-800-829-1040, or by mail. The sooner you contact the IRS, the more options you have. Ignoring the debt does not make it go away — the IRS can place a lien on your property, garnish your wages, or offset future refunds.

How to handle a penalty notice from the IRS

When the IRS assesses a late payment penalty, they send a notice (usually Notice CP14 or similar) showing the penalty amount, the interest charged, and the total due. The notice includes a deadline to respond, typically 30 days. Do not ignore this notice.

If you believe the penalty is wrong — for example, you have proof you paid on time — respond with documentation within the deadline. If you believe you have reasonable cause, submit Form 843 with supporting evidence. If you simply need time to pay, contact the IRS to arrange a payment plan before the deadline passes.

If you disagree with the penalty and the IRS denies your request for relief, you have the right to appeal. The IRS Office of Appeals reviews penalty cases independently. You can request an appeal by filing Form 12203 (Request for Appeals Conference) within the timeframe specified in the IRS notice.

Frequently Asked Questions

Can I get the penalty removed if I pay late but file on time?

You will still owe the failure-to-pay penalty, but you can request it be removed if you have reasonable cause. The IRS may also remove it automatically under First Time Penalty Abatement if you have no penalties in the prior three years and you pay within a certain window after they contact you.

Does the penalty keep growing forever?

The failure-to-pay penalty stops at 25% of the unpaid tax. However, interest continues to accrue daily with no cap, so your total debt keeps rising even after the penalty maxes out.

What if I set up a payment plan with the IRS?

A payment plan stops the failure-to-pay penalty from growing once you are in the plan and making payments on schedule. Interest still accrues on the unpaid balance, but the penalty portion is frozen. Missing a payment can restart the penalty.

How much interest does the IRS charge?

The interest rate changes quarterly and is currently around 8% annually, though it varies by quarter. The IRS publishes the current rate on its website. Interest compounds daily on the tax, penalty, and any previous interest owed.

Can I dispute the penalty if I think the IRS made a mistake?

Yes. Respond to the IRS notice within the deadline with documentation showing the error — for example, proof that you paid on time or that the amount calculated is incorrect. If the IRS denies your request, you can appeal through the Office of Appeals.