Late Filing Penalty Calculator
See exactly what the IRS charges when a return is filed and/or paid after the due date — failure-to-file, failure-to-pay, and interest at the current 7% rate, combined into one total.
Tax still owed as of the original due date (Form 1040 balance due).
Usually April 15 — both the filing AND payment deadline.
Without an extension, both filing and payment were due on the original due date.
Interest and the failure-to-pay penalty run until this date, regardless of when you filed.
The default rate on an unpaid balance. The penalty stops at 25% of the unpaid tax (50 months).
| Item | Deadline used | Months late | Amount |
|---|---|---|---|
| Failure-to-file (5%/mo, reduced by the 0.5% failure-to-pay charge in overlapping months, capped 25%) | 2026-04-15 | 3 | $675.00 |
| Failure-to-pay (0.5%/mo, capped 25%) | 2026-04-15 | 3 | $75.00 |
| Interest (federal short-term rate + 3%, compounded daily) | 2026-04-15 | — | $77.44 |
| Total penalty + interest | $827.44 | ||
How the penalties work
Two separate IRC §6651 penalties can apply to the same unpaid balance, plus interest under IRC §6621/§6622:
- Failure-to-file — 5% of the unpaid tax for each month or part-month the return is late, capped at 25% (5 months). Measured from the filing deadline that actually applied to you — the original due date, or the extended due date if you filed Form 4868.
- Failure-to-pay — 0.5% of the unpaid tax per month or part-month, capped at 25% (50 months). Always measured from the ORIGINAL due date, extension or not — an extension never delays the payment deadline.
- Interest — accrues on the unpaid tax from the day after the original due date until paid, at the IRS's quarterly rate (federal short-term rate + 3 points for individuals), compounded daily.
When both penalties apply in the same month, the failure-to-file penalty is reduced to 4.5% so the combined monthly rate never exceeds 5%. If a return is filed more than 60 days late, a statutory minimum failure-to-file penalty applies even if 5%/month of your (small) unpaid balance would be less — see the calculator's methodology note for the current dollar figure.
The failure-to-pay rate is not always 0.5%. Pick the one that matches your situation in the calculator: it drops to 0.25% per month while an approved IRS payment plan is in effect (only if the return itself was filed on time, IRC §6651(h)), and rises to 1% per month once a final notice of intent to levy has gone unpaid for 10 days (IRC §6651(d)). The 25% ceiling is a share of the unpaid tax, not a month count, so at the 1% rate it arrives after 25 months rather than 50. Note that a payment plan reduces the penalty but never the interest — see the IRS installment agreement calculator to model the payment schedule itself.
This calculator does not model first-time penalty abatement, reasonable-cause waivers, or the fraudulent-failure-to-file penalty.
Reference: current IRS interest rate
The interest portion of this calculator pulls directly from the site's quarterly rate table. See the full IRS interest rates page for the complete 2024–2026 history, corporate and large-corporate rates, and how the rate is set each quarter.
Frequently asked questions
What if I miss the October 15 extended deadline?
If you filed Form 4868 but still file after October 15, the failure-to-file penalty (5% of unpaid tax per month, capped at 25%) starts accruing from October 15 — not from the original April due date. The failure-to-pay penalty and interest, however, have been running from April all along, since the extension never covered payment.
Does a filing extension avoid penalties?
No. Form 4868 gives you six more months to file, not to pay. If you owe tax and don't pay it by the original due date, the failure-to-pay penalty and interest still accrue from that date even with a timely-filed extension. An extension only protects you from the much larger failure-to-file penalty, as long as you file by the extended deadline.
What is the minimum penalty for filing more than 60 days late?
If a return is filed more than 60 days after its due date (including extensions), the failure-to-file penalty cannot be less than a fixed statutory minimum — the smaller of that minimum or 100% of the unpaid tax. The minimum is adjusted for inflation annually; it applies even if the percentage-based calculation would produce a smaller number.
How does the interest compounding work?
Interest on unpaid tax compounds daily at a rate the IRS resets every calendar quarter (currently 7% for individuals) — the federal short-term rate plus 3 percentage points. When the unpaid balance spans a rate change, interest is computed separately for each quarter's segment and chained together, not at a single blended annual rate.
Does an IRS payment plan reduce the failure-to-pay penalty?
Yes — the failure-to-pay penalty drops from 0.5% to 0.25% per month while an approved IRS installment agreement is in effect, but only if you filed the return itself by its due date including extensions (IRC §6651(h)). It does not reduce interest, which keeps compounding daily at the full rate. Going the other way, the penalty rises to 1% per month once a final notice of intent to levy has gone unpaid for 10 days. All three rates share the same 25% ceiling, so at 1% per month the cap is reached after 25 months instead of 50.
Can the failure-to-file and failure-to-pay penalties both apply in the same month?
Yes, but they're coordinated so the combined rate never exceeds 5% of unpaid tax per month. In any month both penalties are running, the failure-to-file penalty is reduced from 5% to 4.5%, and the failure-to-pay penalty adds its usual 0.5% — for a combined 5%, not 5.5%.
Sources
Related insights
Use these guides for rule explanations, planning context, and follow-up questions beyond the calculator result.
IRS tax deadlines 2026 calendar
Every federal deadline from January estimated payments through October extension.
Tax season mistakes to avoid
Common filing errors that cost money — wrong filing status, missed credits, and math traps.
Estimated tax underpayment penalty and safe harbor
110% / 100% prior-year rule, 90% current-year rule, and how Form 2210 works.
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Monthly payment + 7% interest + 0.25%/mo FTP penalty + setup fee. Streamlined ≤$50k/72mo
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