Educational tool · Nothing is saved or sent
IRS penalty and interest estimator
Unpaid tax grows through interest and penalties. This tool shows roughly how much, so you can judge whether acting sooner matters. It is an estimate, not a payoff figure, and you enter the interest rate yourself so the tool never relies on an outdated one.
Enter the unpaid tax, the months unpaid and the current IRS interest rate to see a rough estimate.
How the estimate works
- Failure-to-pay penalty: 0.5% of the unpaid tax per month, up to 25%. It drops to 0.25% per month while you are on an approved installment agreement, if the return was filed on time.
- Failure-to-file penalty: when a return is late, 4.5% per month for up to 5 months, on top of the failure-to-pay penalty.
- Interest: compounds daily at the rate you enter, on the unpaid tax only.
What this estimate leaves out
- Interest charged on the penalties themselves, so the real total is usually somewhat higher.
- The minimum penalty for returns more than 60 days late, other penalty types, and rate changes between quarters.
- Penalty relief you may qualify for, such as first-time abatement. Relief is decided by the IRS and is not guaranteed.
Always rely on the balance printed on your IRS notice or shown in your online account. Official references: IRS penalties and IRS interest.