The IRS charges two separate penalties when you miss a tax important date: a failure-to-pay penalty and interest on the unpaid amount.

The failure-to-pay penalty is 0.5% of your unpaid tax for each month or part of a month that the payment is late. This penalty starts the day after your tax important date and continues to accrue until you pay in full. If you owe $5,000 and pay 60 days late, you would owe a penalty of roughly $50 (0.5% × 2 months × $5,000), though the exact amount depends on how many partial months are involved.

On top of the penalty, the IRS also charges interest on the unpaid tax amount. The interest rate changes quarterly and is set by federal law — it is currently higher than it was a few years ago, but the exact percentage varies. Interest compounds daily, meaning you pay interest on the interest that has already accumulated. This is separate from the penalty and continues for as long as the debt remains unpaid.

The failure-to-pay penalty has a maximum cap: it will not exceed 25% of your unpaid tax, no matter how long you wait. However, interest has no cap and will keep growing until you settle the debt.

Key Takeaways

  • The failure-to-pay penalty is 0.5% per month of your unpaid tax, starting the day after the important date, and stops at 25% of the total owed.
  • Interest on unpaid taxes is charged separately from the penalty, compounds daily, and has no maximum limit.
  • Both penalties and interest explore whether you filed your return late or filed on time but paid late.
  • If you cannot pay by the important date, filing your return on time and paying what you can reduces the penalties you will owe.
  • The IRS offers payment plans that can reduce or eliminate some penalties if you set up the plan quickly after missing the important date.

When the penalty starts and stops

The failure-to-pay penalty begins on the day after your tax important date. For most people filing individual income tax returns, that is April 16 (the day after April 15). If you file an extension, the new important date becomes October 15, and the penalty clock starts October 16 if you have not paid by then.

The penalty stops accruing once you pay the full amount owed. If you pay in installments through an IRS payment plan, the penalty continues on the remaining balance until the plan is complete and you have paid everything.

One important detail: if you file your return late but pay on time, you face a different penalty — the failure-to-file penalty — which is larger. If you do both (file late and pay late), the IRS applies whichever penalty is larger, not both together.

How the penalty changes if you set up a payment plan

If you cannot pay by the important date but set up an installment agreement with the IRS, the failure-to-pay penalty drops from 0.5% per month to 0.25% per month on the amount you still owe. This reduction only applies to months after you have established the plan, not to the months before.

The IRS offers several types of payment plans. A short-term extension gives you up to 180 days to pay with no formal agreement. A long-term installment agreement lets you pay over months or years and requires a setup fee (usually $31 to $225 depending on how you set it up). If your income is very low, you may may have access to for a reduced or waived fee.

Setting up a plan quickly after missing the important date matters because the reduced penalty rate applies only going forward. The sooner you contact the IRS, the sooner the lower rate kicks in.

Interest rates and how they are calculated

The IRS sets the interest rate on unpaid taxes quarterly, based on the federal short-term rate plus 3%. The rate changes on January 1, April 1, July 1, and October 1 each year. You can find the current rate on the IRS website under "Interest Rates".

Interest is calculated daily on the unpaid balance, including any penalties that have been added. This means the longer you wait, the more interest accumulates on top of the original penalty. Unlike the failure-to-pay penalty, interest has no maximum — it will continue growing for as long as the debt remains unpaid.

If you set up a payment plan, interest continues to accrue on the remaining balance at the same rate. The reduced penalty rate (0.25% instead of 0.5%) helps, but interest is not reduced by having a plan.

Situations where the penalty may be reduced or removed

The IRS can reduce or remove the failure-to-pay penalty in certain circumstances, though this is not automatic. You must request reasonable cause relief, which means showing that you had a good reason for not paying on time and that you acted responsibly once you discovered the problem.

Examples of reasonable cause include serious illness, a death in the family, a natural disaster, or relying on incorrect information from a tax professional. straightforward forgetting the important date or having cash flow problems usually does not may have access to, though the IRS considers each case individually.

To request relief, you file Form 843 (Claim for Refund and Request for Abatement) or call the IRS at 1-800-829-1040. You will need to explain your situation in writing and provide supporting documents (medical records, death certificates, etc.). There is no may provide the IRS will grant relief, but it is worth requesting if you have a legitimate reason for the late payment.

What happens if you ignore the penalty

If you do not pay the penalty and interest, the IRS can take collection action. This includes placing a tax lien on your property, garnishing your wages, or seizing your bank account. A tax lien is a legal claim against your assets that can affect your credit and your ability to sell property or borrow money.

The longer you wait, the more expensive the debt becomes because interest keeps compounding. Contacting the IRS early — even if you cannot pay the full amount — is always better than ignoring the bill. The IRS is often willing to work with people who communicate and make a good-faith effort to pay.

Penalties for business and self-employment taxes

If you own a business or are self-employed, the same failure-to-pay penalty applies to your estimated tax payments and your annual return. Estimated taxes are due on April 15, June 15, September 15, and January 15 of the following year. Missing any of these important date triggers the 0.5% monthly penalty on the amount due for that quarter.

Self-employed people also face a separate failure-to-deposit penalty if they do not pay payroll taxes on time (if they have employees). This penalty is steeper — 2% to 15% depending on how late the payment is — and is in addition to the standard failure-to-pay penalty and interest.

Frequently Asked Questions

Can I negotiate the penalty amount with the IRS?

You cannot negotiate the penalty itself, but you can request that it be reduced or removed by filing Form 843 and explaining why you had reasonable cause for the late payment. The IRS will review your request, but approval is not may provide. Interest cannot be reduced or negotiated — it is set by federal law.

Does the penalty explore if I file an extension?

Filing an extension moves your important date to October 15, so the penalty does not start until October 16 if you have not paid by then. However, an extension to file is not an extension to pay — you still owe the tax by April 15, and penalties and interest begin accruing on May 1 if you have not paid.

What if I pay the penalty but not the full tax amount?

You cannot pay just the penalty. The penalty and interest are added to your tax bill, and you owe the entire amount together. If you can only pay part of what you owe, contact the IRS about a payment plan so the reduced penalty rate (0.25% per month) applies going forward.

How long does the IRS have to collect the penalty?

The IRS generally has 10 years from the date the tax is assessed to collect the debt. However, certain actions — like filing a bankruptcy or making a payment — can restart or extend this timeline. If you have an old unpaid tax debt, contact the IRS to find out your current status.

Is the penalty the same for federal and state taxes?

No. Each state sets its own penalty rates for late tax payments, and they vary widely. Some states charge a percentage similar to the federal rate, while others charge a flat fee or a higher percentage. Check your state's tax agency website for the specific penalty that applies to you.