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 a failure-to-pay penalty and failure-to-pay interest to what you owe. These are not the same thing. The penalty is a flat percentage of the unpaid tax. The interest compounds daily and is much larger over time. Both start the day after your payment was due.
The failure-to-pay penalty is 0.5% of your unpaid tax for each month or part of a month that the tax remains unpaid. If you owe $10,000 and pay three months late, you owe a $150 penalty (0.5% × 3 months × $10,000). The maximum penalty is 25% of your unpaid tax, which means the penalty stops growing once you've been late for 50 months.
Interest accrues on top of both the original tax and the penalty. The IRS sets the interest rate quarterly—it's the federal short-term rate plus 3 percentage points. For 2024, the rate is 8% per year, compounded daily. On that same $10,000 owed for three months, interest alone would be roughly $200.
Key Takeaways
- The failure-to-pay penalty is 0.5% per month of unpaid tax, capped at 25% total.
- Interest compounds daily at a rate the IRS sets each quarter, currently 8% annually for most taxpayers.
- Both penalties and interest begin the day after your tax deadline and grow until you pay in full.
- Paying even a partial amount before the deadline reduces the penalty and interest on the remaining balance.
- The IRS can reduce or remove penalties if you have a reasonable cause, such as serious illness or a death in your family.
How the penalty and interest stack together
The failure-to-pay penalty and interest work independently but both apply to your account. You pay the original tax, plus the penalty, plus the interest on all three amounts. This means the longer you wait, the faster the total grows.
A concrete example: you owe $5,000 in federal income tax due April 15. You pay on July 15—three months late. Your bill is $5,000 (original tax) + $75 (penalty: 0.5% × 3 × $5,000) + roughly $100 (interest on $5,000 for three months at 8% annually) = $5,175. If you wait six months instead, the penalty doubles to $150, and interest climbs to roughly $200, bringing your total to $5,350.
Interest is calculated on the unpaid tax plus any penalties already added. This is why the total grows faster the longer you delay. After one year of non-payment, interest alone often exceeds the original penalty.
When the IRS might reduce or remove the penalty
The IRS does not automatically forgive late-payment penalties, but you can request reasonable cause relief if you have a legitimate reason for the delay. Common reasons the IRS accepts include serious illness or hospitalization, a death in your immediate family, unavoidable absence from home, or reliance on a professional tax preparer who made an error.
To request relief, file Form 843 (Claim for Refund and Request for Abatement) with the IRS. Include a written explanation of why you paid late and any supporting documents—a hospital discharge summary, a death certificate, or correspondence from your tax preparer, for example. The IRS typically responds within 60 days.
Reasonable cause relief does not remove interest. Interest continues to accrue from the original due date until you pay. The IRS can only remove or reduce the penalty itself, not the interest charges.
Penalties for installment agreements and payment plans
If you set up an installment agreement with the IRS to pay over time, the failure-to-pay penalty is reduced to 0.25% per month instead of 0.5%—half the normal rate. This applies only to months when you are actively making payments under the agreement. If you miss a payment on the plan, the penalty reverts to 0.5% for that month and any subsequent months until the agreement is back on track.
The interest rate does not change with an installment agreement. You still owe daily interest at the current IRS rate on the full unpaid balance, including penalties.
Setting up a payment plan before the deadline is one of the most effective ways to reduce what you owe. Even if you cannot pay the full amount due, contacting the IRS and arranging a plan lowers your penalty by half and shows the IRS you are making a good-faith effort to pay.
State tax penalties for late payment
Most states charge their own late-payment penalties on top of federal penalties. State penalties vary widely. Some states charge 5% to 10% of unpaid tax per month, while others use a flat percentage or a tiered system that increases the longer you wait. A few states charge no penalty if you pay within a certain grace period.
State interest rates also vary. Some states tie their rate to the federal rate; others set their own. You need to contact your state tax authority to learn the exact penalty and interest rate for your situation. The state department of revenue website usually lists current rates, or you can call the department directly.
If you owe both federal and state tax, paying one does not satisfy the other. You must pay each separately to stop penalties and interest from accruing on each account.
What happens if you ignore the debt
Unpaid federal tax debt does not disappear. The IRS can place a tax lien on your property, garnish your wages, seize your bank account, or offset future refunds. The IRS can also refer your case to a private collection agency, which will contact you by phone and mail.
The longer you wait, the more you owe. After 10 years, the IRS can no longer collect most tax debts through normal means, but this is a long time to carry the debt, and the IRS can extend the collection period if you don't respond to notices or if you move frequently.
If you cannot pay in full, contact the IRS immediately. An installment agreement, an offer in compromise, or currently not collectible status can all stop or slow the accumulation of penalties and interest while you work out a payment plan.
How to pay late tax and stop penalties from growing
Pay as soon as you realize you owe. The IRS accepts payments online through IRS.gov, by phone, by mail, or through an authorized payment processor. Online payment is fastest and gives you a confirmation number immediately.
If you cannot pay the full amount, pay whatever you can. A partial payment reduces the penalty and interest on the remaining balance. Then contact the IRS to set up a payment plan for what's left. This cuts your monthly penalty rate in half and shows the IRS you are serious about resolving the debt.
Keep records of every payment you make, including the date and amount. The IRS applies payments to your oldest tax year first, then to penalties and interest. Knowing exactly what you've paid helps you track your progress and verify that the IRS has credited your account correctly.
Frequently Asked Questions
Does the penalty stop growing after a certain point?
Yes. The failure-to-pay penalty maxes out at 25% of your unpaid tax. Once you reach that cap—typically after 50 months of non-payment—the penalty stops growing. Interest, however, continues to accrue until you pay in full.
Can I remove the interest charges, or just the penalty?
The IRS can only remove or reduce the penalty, not the interest. Interest is considered a charge for the time value of money and is not subject to reasonable cause relief. You must pay all accrued interest when you settle your debt.
What if I set up a payment plan but then miss a payment?
Missing a payment on an installment agreement causes the reduced 0.25% penalty to revert to the full 0.5% for that month and any following months until you catch up. Contact the IRS immediately if you miss a payment to discuss your options and get back on track.
Do state penalties apply on top of federal penalties?
Yes. Most states charge their own late-payment penalties and interest separately from federal charges. You must pay both the IRS and your state tax authority to stop penalties from growing on each account. State rates vary by state.
How long does the IRS have to collect the debt?
The IRS generally has 10 years from the date the tax was assessed to collect. However, the IRS can extend this period if you don't respond to notices, move frequently, or take other actions that delay collection. Paying or setting up a plan stops the clock from running.