The IRS charges two separate penalties when you miss a tax payment deadline

If you owe federal income tax and don't pay by the due date, the IRS adds two costs on top of what you already owe: a failure-to-pay penalty and interest. The penalty is 0.5% of your unpaid tax for each month or part of a month that the tax remains unpaid, up to 25% total. Interest compounds daily at a rate set by the IRS each quarter—currently around 8% annually, though this changes. Both start accruing the day after the tax deadline passes.

The penalty clock stops once you've paid in full or entered a payment plan with the IRS. If you file your return late and owe tax, you may face an additional failure-to-file penalty on top of the failure-to-pay penalty, though the IRS reduces the failure-to-file penalty by the amount of the failure-to-pay penalty if both apply in the same month.

Key Takeaways

  • The failure-to-pay penalty is 0.5% of unpaid tax per month, capped at 25% total, and starts the day after the tax deadline.
  • Interest accrues daily on unpaid tax at a rate the IRS sets each quarter, currently around 8% annually.
  • Setting up a payment plan with the IRS stops the penalty from growing further and may reduce the interest rate slightly.
  • If you file your return late and owe tax, you face both a failure-to-file and failure-to-pay penalty, though they partially offset each other.
  • Penalties and interest are separate from the tax itself and are added to your total bill.

How the failure-to-pay penalty works month by month

The penalty accrues at 0.5% per month for each full or partial month your tax remains unpaid. If you owe $5,000 and pay one month late, you owe $25 in penalties (0.5% of $5,000). If you pay three months late, the penalty is $75. The penalty stops growing once you pay or set up a payment plan, and it cannot exceed 25% of your original unpaid tax.

The IRS counts any part of a month as a full month. If your tax was due April 15 and you pay on April 16, that counts as one month for penalty purposes. This means even a few days of delay can add up if you wait weeks or months to pay.

Interest compounds daily on top of penalties

While the penalty is a flat percentage per month, interest works differently. The IRS charges interest on your unpaid tax and on the penalties themselves, compounded daily. The interest rate changes quarterly and is published by the IRS—it is currently around 8% annually, but check IRS.gov for the current quarter's rate if you need the exact figure.

Interest is not capped and will continue to grow as long as the debt remains unpaid. Over a year, interest alone can nearly double what you owe. This is why paying as soon as possible, even if you cannot pay the full amount, reduces the total cost significantly.

What happens if you set up a payment plan

If you cannot pay in full by the deadline, the IRS allows you to set up an installment agreement to pay over time. Once you enter a payment plan, the failure-to-pay penalty rate drops from 0.5% per month to 0.25% per month. Interest continues to accrue, but at least the penalty growth slows.

You can request a payment plan online through IRS.gov, by phone at 1-800-829-1040, or by mail. Short-term plans (120 days or fewer) are free. Long-term plans charge a setup fee, usually $31 to $225 depending on how you set it up and your income level. The fee is added to your first payment.

State tax penalties vary by state

If you owe state income tax, each state sets its own penalty and interest rates. Some states charge penalties similar to the federal rate (around 0.5% per month), while others charge more. A few states charge no penalty if you pay within a grace period of a few days or weeks. Check your state tax agency's website for the exact rate—search "[your state] late payment penalty" to find it quickly.

State interest rates also vary. Some states charge 6% to 8% annually, while others charge 10% or more. If you owe both federal and state tax, you will owe penalties and interest to each separately.

How to minimize penalties if you are already late

If you have missed the deadline, pay as soon as you can. The sooner you pay, the less interest accrues. If you cannot pay the full amount, send whatever you can—the IRS will apply it to your account and reduce the total interest owed.

If you have a valid reason for the late payment—such as a serious illness, natural disaster, or death in the family—you can request penalty relief from the IRS. This is called "reasonable cause" relief. You must file Form 843 (Claim for Refund and Request for Abatement) and explain the reason. The IRS does not grant relief for simple forgetfulness or lack of funds, but it does consider circumstances beyond your control. Send Form 843 to the IRS address listed in your notice.

Penalties on estimated tax payments

If you are self-employed or have income not subject to withholding, you may owe estimated tax payments four times a year. Missing an estimated tax payment deadline also triggers a penalty, though it is calculated differently. The IRS charges interest on the underpayment from the due date of that quarter until you pay, plus a penalty that varies based on the interest rate. The penalty is not a flat percentage like the failure-to-pay penalty; instead, it is tied to the IRS interest rate for that quarter.

If you miss one estimated payment but catch up on the next one, the penalty applies only to the missed quarter, not to your entire tax bill. This is why it matters to pay estimated tax on time even if you expect to owe more or less at tax time.

Frequently Asked Questions

Can the IRS remove penalties if I have a good reason for paying late?

Yes, through reasonable cause relief. The IRS considers circumstances like serious illness, death in the family, or natural disaster. File Form 843 and explain the reason. Lack of funds or simple forgetfulness typically do not may have access to, but the IRS does grant relief in genuine hardship cases.

Does the penalty stop growing if I set up a payment plan?

The penalty rate drops from 0.5% to 0.25% per month once you enter a payment plan, but it continues to accrue until you pay in full. Interest also continues to compound daily. The plan slows the growth but does not stop it.

What if I pay part of my tax bill but not all of it?

The IRS applies your payment to your account and reduces the unpaid balance. Penalties and interest continue to accrue only on the remaining unpaid amount. Paying anything reduces the total cost compared to waiting to pay the full amount later.

Do state taxes have the same penalties as federal taxes?

No. Each state sets its own penalty and interest rates. Some charge similar rates to the federal IRS (around 0.5% per month), while others charge more or less. Check your state tax agency's website for the exact rate that applies to you.

What if I cannot pay at all right now?

Contact the IRS at 1-800-829-1040 to discuss options. You may be able to set up a payment plan, request a temporary delay, or explore an offer in compromise if your financial situation is severe. The longer you wait without contacting the IRS, the more penalties and interest accumulate.