IRS Penalty and Interest Calculator
Filed late or can't pay? Estimate the IRS failure-to-file penalty, failure-to-pay penalty, and daily-compounded interest on your unpaid taxes — month by month, using the official 2026 rates.
The balance due shown (or expected) on your return.
Total you'll owe
$5,820.74
tax + penalties + interest by Jul 2, 2026
Added by the IRS
$820.74
16.4% of your unpaid tax
Failure-to-file
$675.00
3 mo
Failure-to-pay
$75.00
3 mo @ 0.5%
Interest
$70.74
compounded daily
Breakdown
Month-by-Month Accrual
| Through | Late filing | Late payment | Interest | Total owed |
|---|---|---|---|---|
| May 15, 2026 | +$225.00 | +$25.00 | +$25.95 | $5,275.95 |
| Jun 15, 2026 | +$225.00 | +$25.00 | +$28.23 | $5,554.18 |
| Jul 15, 2026 | +$225.00 | +$25.00 | +$16.56 | $5,820.74 |
Waiting 3 more months adds $635
Penalties accrue for every month or part of a month, and interest compounds daily. Filing and paying even one month sooner cuts the bill.
File even if you can't pay
The late-filing penalty (5%/month) is ten times the late-payment penalty (0.5%/month). Filing now and paying later almost always beats waiting — and a payment plan cuts the pay penalty in half.
Estimate for individual Form 1040 balances. Assumes penalties join the interest-bearing balance as they accrue, and does not model the 1% post-levy rate, disaster postponements, or penalty abatement. The IRS bills the exact amount with your notice.
How This Calculator Works
Count the late months
Each month — or any part of a month — past the deadline adds 5% for not filing (max 25%) and 0.5% for not paying (max 25%), exactly as IRC §6651 prescribes.
Apply the fine print
Concurrent months are netted (4.5% + 0.5%), the 60-day minimum penalty kicks in when it should, extensions move only the filing clock, and installment agreements halve the pay penalty.
Compound the interest daily
Interest runs at the federal short-term rate + 3% on tax and penalties, day by day, using each quarter's actual published IRS rate.
Three ways to shrink the bill
Penalties are not always final. The IRS removes millions of dollars of them every year — if you ask the right way.
First-time abatement
Clean penalty history for the past 3 years and current on all filings? The IRS removes FTF and FTP penalties on request — often with a single phone call. Interest tied to the removed penalty goes too.
Reasonable cause
Serious illness, natural disaster, destroyed records, or bad written advice from the IRS can qualify. Document the facts and dates; sustained relief removes the penalty and its interest.
Payment plan
Short-term plans (up to 180 days) cost $0 to set up. Long-term installment agreements cost $22 online with direct debit ($69 otherwise) and cut the failure-to-pay rate from 0.5% to 0.25% per month.
Interest itself cannot be abated by law — it only falls away with the penalty it accrued on (IRS penalty relief rules).
What This Calculator Includes
Both §6651 penalties
Failure-to-file and failure-to-pay, with the 4.5%/0.5% concurrent-month netting and the 25% caps.
The 60-day minimum
Applies the $525 / $510 / $485 minimum late-filing penalty (by due-date year) when a return is 60+ days late.
Real quarterly rates
8% (2024), 7% (2025), and 7% / 6% / 7% through Q3 2026 — compounded daily on tax plus penalties.
Extension & plan aware
Extensions move only the filing clock; approved installment agreements halve the monthly pay penalty.
Why Use This Calculator?
Know the real number
IRS notices arrive weeks later. See tax + penalties + interest now, so the CP14 letter is no surprise.
Compare your options
Toggle the installment agreement, move the payment date, or test filing today vs next month — the month-by-month table shows exactly what each choice costs.
Act on the cheapest fix
The math makes one thing obvious: filing is urgent, paying can be arranged. That insight alone saves most people hundreds of dollars.
Frequently Asked Questions
The three charges the IRS stacks on a late return
When you miss the April deadline with a balance due, three separate charges accrue under IRC §6651 and IRC §6621:
| Charge | Rate | Cap | Clock starts |
|---|---|---|---|
| Failure-to-file | 5% per month or part-month (4.5% when both penalties run) | 25% (5 months) | Filing deadline, including extensions |
| Failure-to-pay | 0.5% per month (0.25% on a payment plan, 1% after a levy notice) | 25% (50 months) | Original April deadline — extensions do not help |
| Interest | Federal short-term rate + 3%, compounded daily (7% in Q3 2026) | None | Original April deadline, on tax and penalties |
Two details catch most people out. First, a part of a month counts as a full month — filing on May 20 costs two months of penalties, not one. Second, if your return is more than 60 days late, a minimum failure-to-file penalty applies: the lesser of $525 (returns due in 2026; $510 for 2025, $485 for 2024) or 100% of the unpaid tax — painful on small balances.
A worked example: $10,000 paid three months late
Say your 2025 return was due April 15, 2026, you owe $10,000, and you file and pay on July 10, 2026 — three part-months late:
- Failure-to-file: 3 months × 4.5% (reduced because the pay penalty runs too) = 13.5% × $10,000 = $1,350
- Failure-to-pay: 3 months × 0.5% = 1.5% × $10,000 = $150
- Interest: 86 days at 6% (Q2 2026) then 7% (Q3), compounded daily on tax plus penalties ≈ $159
Total: about $11,659 — the IRS added $1,659, or 16.6% of the tax, in just three months. Had the same person filed on time in April and simply paid late in July, the failure-to-file penalty would vanish and the add-on would drop to roughly $297. That is why the single most valuable move is always to file, even if you cannot pay.
Extensions, payment plans, and how to stop the meter
Form 4868 extensions move the filing deadline to October 15 but not the payment deadline — interest and the 0.5% pay penalty still run from April. (If you pay at least 90% of the actual tax by April, the pay penalty is generally waived for the extension period.)
Payment plans stop enforced collection and cut the pay penalty to 0.25% per month: a short-term plan (up to 180 days) has no setup fee, while a long-term installment agreement costs $22 to set up online with direct debit ($69 with other payment methods; low-income taxpayers can have fees waived or reimbursed). Interest continues on any plan, so paying faster always wins.
Already been charged? Ask about first-time abatement if your record is clean, or reasonable-cause relief if events beyond your control caused the lapse. And if your problem is quarterly estimated payments that were too small during the year — a different penalty under IRC §6654 — use our estimated tax penalty calculator instead.
Official References
Sources used for the rates and rules in this calculator (verified July 2026):
- IRS: Failure to File Penalty (IRC §6651(a)(1))
The 5%/month rate, 25% cap, concurrent-month reduction, and minimum-penalty table.
- IRS: Failure to Pay Penalty (IRC §6651(a)(2))
The 0.5%/month rate, 0.25% installment-agreement rate, and 1% post-levy rate.
- IRS: Interest on Underpayments (IRC §6621, §6622)
How interest accrues from the due date on tax and penalties, compounded daily.
- IRS: Quarterly Interest Rates
The published quarterly rates used here, including 7% for Q3 2026 (Rev. Rul. 2026-10).
- IRS: Payment Plans and Installment Agreements
Short-term and long-term plan options, setup fees, and low-income relief.
- IRS Publication 505: Tax Withholding and Estimated Tax
Background on paying tax during the year and avoiding penalties.
This calculator provides an estimate for individual income tax balances. The IRS computes the binding amounts on its notices, and relief programs can reduce them. Consult a qualified tax professional about your specific situation.
Related Tools
Estimated Tax Penalty Calculator
The Form 2210 underpayment penalty for quarterly estimates paid short.
OpenQuarterly Tax Calculator
Size your estimated payments so next year has no penalties at all.
OpenTax Deadline Calendar
Every federal filing and payment deadline in one place.
OpenSelf-Employment Tax Calculator
Figure the tax bill behind the balance due.
OpenYour first month of Jupid — completely free
New here? Enter this code at checkout and your first month is on us — full AI bookkeeping, tax filing, and a 24/7 accountant, $0 for 30 days.
New customers. First month free with code NEW2026, cancel anytime.