If you filed your federal income tax return late, or paid late, the IRS adds two separate
penalties plus interest. This page explains how each one is calculated, using the IRS’s own
published rules, and links to a calculator that works out the amount for your dates and figures.
Everything here comes from two public sources: the penalty rules in
26 CFR 301.6651-1 and the
IRS Internal Revenue Manual at
IRM 20.1.2.
The figures on this page were taken from those sources on 2026-08-28.
Open the late filing and payment penalty calculator to enter your own
dates and amounts.
The two penalties are separate, and they are not the same size
Filing late and paying late are two different failures, and the IRS charges for each one.
The failure-to-file penalty runs at 5 percent of the unpaid tax per month, while the
failure-to-pay penalty runs at a much smaller 0.5 percent per month
(26 CFR 301.6651-1).
A partial month counts as a whole month for both penalties, so a return filed one day late is
charged the same as one filed three weeks late
(IRM 20.1.2).
Each penalty stops growing once it reaches 25 percent of the unpaid tax, and the two caps are
counted separately
(IRM 20.1.2.3.8.1).
When both penalties apply in the same month, the IRS subtracts the failure-to-pay amount from
the failure-to-file amount for that month, so you are not charged twice for the same month
(IRC 6651(c)(1)).
Paying late is charged on the balance at the start of each month
The failure-to-pay penalty is not a flat percentage of your original bill. It is recalculated
each month against whatever was still unpaid when that month began
(IRM 20.1.2.3.8.2).
This is why the date of every payment matters, not just the total. A payment made on the first
of a month reduces that month’s penalty; the same payment made two weeks later does not, because
the penalty for that month was already fixed when the month started
(IRM 20.1.2.3.8.4.1).
Two situations change the monthly rate. If you filed on time and later entered an installment
agreement, the rate drops to 0.25 percent for any month the agreement is in effect — but only if
the return itself was filed by the due date, including extensions
(IRM 20.1.2.3.8.1.2).
Most people looking up late-filing penalties do not qualify for that reduction.
If you are more than 60 days late, a minimum penalty can replace the calculation
When a return is more than 60 days late and the normal failure-to-file calculation comes out
small, the IRS charges a fixed minimum instead
(IRM 20.1.2.3.7.4).
The minimum depends on when the return was originally due, without extensions, and it is adjusted
for inflation. For returns due during 2026 the minimum is $525, and for returns due after that it
rises to $535
(IRM 20.1.2.3.7.4).
For older returns the figures were lower: $510 for 2025, $485 for 2024, and $435 for returns due
between 2020 and 2022
(IRM 20.1.2.3.7.4).
If the unpaid tax is smaller than the minimum, the penalty is the unpaid tax rather than the
table amount, so the minimum can never exceed what you actually owed
(IRM 20.1.2.3.7.4).
The minimum applies to income tax returns only, not to employment, excise, gift, or estate tax
returns
(IRM 20.1.2.3.7.4).
A worked example from the IRS manual
The IRS publishes worked examples, and the calculator on this site reproduces them exactly. Here
is one of them, taken directly from the manual
(IRM 20.1.2.3.8.7.1).
Example — a return filed three months late with a partial payment
- return_due_date
- 2022-04-15
- extended_due_date
- tax_required_to_be_shown
- 5000
- paid_by_due_date
- 0
- filing_date
- 2022-07-13
- payments_after_due_date
- 2022-06-01:2000|2022-07-13:3000
- calculation_through_date
- 2022-07-13
- installment_start_date
- failure_to_file_penalty
- 685.00
- failure_to_pay_penalty
- 65.00
- total_penalty
- 750.00
The manual walks through the same case in prose: the return was three months late, the penalty
for paying late over those months came to $65, and the failure-to-file penalty was reduced by
that amount
(IRM 20.1.2.3.8.7.1).
Run the same figures through the calculator and you will get the same
answer.
Interest is charged on top, and the rate changes every quarter
Interest runs on unpaid tax from the original due date until it is paid, compounds daily, and has
no cap
(IRS quarterly interest rates).
The rate is reset by the IRS every quarter, so a single balance can be charged at several
different rates over its life. For the third quarter of 2026 the underpayment rate is 7 percent,
after a quarter at 6 percent
(IRS Notice 746).
The calculator splits your period at each rate change and shows the amount added in each segment
(IRS Notice 746).
What this page does not cover
This is an estimate, and the amount the IRS actually bills you can differ. The IRS calculates
penalties and interest from its own records of your account, and those records may include
payments, credits, or adjustments that are not entered here
(IRM 20.1.2).
The calculator covers the standard late-filing and late-payment penalties on a personal federal
income tax return only. It does not cover state or local tax, business or information returns,
fraud penalties, accuracy-related penalties, estimated tax penalties, or any request for penalty
relief such as reasonable cause or first-time abatement
(IRM 20.1.2).
This page is not tax advice. It explains published IRS rules and applies them to
the figures you enter. For advice about your own situation, or before responding to an IRS
notice, talk to a tax professional
(IRM 20.1.2).