Imagine you owe the IRS $10,000 this year and money is tight, so you do nothing — no return, no payment. By doing nothing, you just chose the most expensive option on the menu. Within five months, penalties alone add $2,250 to your bill, and if you keep ignoring it, penalties can climb to $4,750 on top of the original tax — before a single day of interest. Now imagine you had filed the return on time and simply paid late: after those same five months, your penalty would be about $250 instead of $2,250.
That ten-to-one difference is the single most important thing to understand about IRS late penalties. Filing and paying are punished separately, at wildly different rates, and the failure-to-file penalty is the one that destroys people. This guide walks through exactly how both penalties work under Internal Revenue Code Section 6651, how they combine, the traps that make them worse, and the two straightforward ways to get them removed.
The Two Penalties Under Section 6651
Section 6651 imposes two separate "additions to tax" — the statute's term for what everyone else calls penalties. They run on different clocks and at different speeds.
Failure to File: 5% Per Month, Up to 25%
If you don't file your return by the due date (including extensions), the IRS charges 5% of the unpaid tax for each month or part of a month the return is late, up to a maximum of 25%. That cap is reached after five months.
Two details matter here:
- "Part of a month" counts as a whole month. File one day late and you owe a full 5% for that month. The IRS applies full monthly charges even if you fix the problem days into the month.
- The penalty is based on unpaid tax. If your withholding and estimated payments already cover your full liability — or you're owed a refund — the 5% applies to zero, which is zero. There is generally no failure-to-file penalty when no tax is due, though you should still file to claim your refund (you generally have three years to do so).
Failure to Pay: 0.5% Per Month, Up to 25%
If you don't pay the tax shown on your return by the due date, the IRS charges 0.5% of the unpaid amount for each month or part of a month it remains unpaid, up to a maximum of 25%. Because the monthly rate is one-tenth of the filing penalty, this cap takes 50 months — more than four years — to reach.
Note the asymmetry: the filing penalty maxes out in five months, while the payment penalty grinds on for years. This is deliberate. Congress wants your return first and foremost — an unfiled return means the IRS doesn't even know what you owe.
How the Two Penalties Stack to 47.5%
When you both fail to file and fail to pay, the two penalties don't simply add to 5.5% per month. Section 6651(c)(1) provides a coordination rule: for any month both penalties apply, the failure-to-file penalty is reduced by the failure-to-pay penalty for that month.
Here's what that looks like in practice:
- Months 1–5: Instead of 5% + 0.5%, you pay 4.5% (file) + 0.5% (pay) = 5% per month combined. After five months, the filing portion is 22.5% and the payment portion is 2.5%, for a combined 25%.
- Month 6 onward: The filing penalty has maxed out at 22.5% (not 25%, because of the monthly reduction), but the payment penalty keeps running at 0.5% per month until it hits its own 25% cap.
- The grand total: 22.5% + 25% = 47.5% of your unpaid tax in penalties alone.
On a $10,000 balance, that's up to $4,750 in penalties — nearly half the original debt again. And interest, covered below, piles on top of all of it.
A Concrete Example
Say you owe $10,000 for 2025, file your return four months late, and pay in full at that point:
- Failure to file: 4.5% × 4 months = 18% = $1,800
- Failure to pay: 0.5% × 4 months = 2% = $200
- Total penalties: $2,000
Now compare: if you had filed on time and paid four months late, you'd owe only the $200 payment penalty. Filing on time saved $1,800 — 90% of the penalties. That is why every tax professional repeats the same mantra: file even if you can't pay.
Four Traps That Make Penalties Worse
1. The 60-Day Minimum: $525 Even on Small Balances
If your return is more than 60 days late, a minimum penalty kicks in: for returns due after December 31, 2025, it's the lesser of $525 or 100% of the unpaid tax. (For 2025-due returns it was $510; the figure adjusts annually for inflation.)
This floor bites hardest on small balances. Owe $400 and file three months late? The percentage math says 4.5% × 3 = $54, but the 60-day rule raises it to $400 — the entire amount you owed, doubled. Only if your balance exceeds $525 does the percentage calculation take over.
2. Fraudulent Failure to File: 15% Per Month, Up to 75%
If the IRS determines your failure to file was fraudulent — meaning you deliberately intended to evade tax, not merely that you were disorganized — the filing penalty jumps to 15% per month with a 75% cap. The line between negligence and fraud is about intent: keeping two sets of books, hiding income, or using false Social Security numbers points toward fraud; losing track of a deadline does not. Most late filers never face this, but it exists as a ceiling you never want to approach.
3. Ignoring a Levy Notice: The Rate Doubles to 1%
If the IRS sends you a notice of intent to levy and you still don't pay within 10 days, the failure-to-pay rate jumps from 0.5% to 1% per month. A levy notice is the IRS telling you it is preparing to seize assets — bank accounts, wages, property. At that stage, the higher penalty rate is the least of your problems, but it adds insult to an already serious situation.
4. Interest Runs on Everything, Compounded Daily
Penalties aren't the only add-on. Under Section 6601, interest accrues on unpaid tax — and on the penalties themselves once assessed — from the original due date until you pay in full. The rate resets quarterly based on the federal short-term rate plus 3 percentage points, and it compounds daily. For the quarter beginning October 1, 2026, the individual underpayment rate is 7% per year, compounded daily.
Unlike penalties, interest generally cannot be abated for reasonable cause. It stops growing only when the underlying balance is paid. This is another reason to pay anything you can as early as you can: every dollar you send stops accruing both the 0.5% monthly penalty and daily interest on that dollar.
Filing on Time Is Always the Cheapest Move
Three practical rules fall out of the math above:
An extension gives you more time to file, not more time to pay. Filing Form 4868 (individuals) or Form 7004 (businesses) moves your filing deadline — typically to October 15 — and avoids the failure-to-file penalty if you meet the extended date. But the tax itself is still due on the original April deadline, and the 0.5% failure-to-pay penalty plus interest run from that date on any unpaid balance. Always pay what you can with the extension request, even if it's a partial payment.
File a return you can't pay in full. As the example above showed, filing on time while paying four months late costs $200 in penalties versus $2,000 for filing late too. A timely return with a balance due also starts the clock on options like installment agreements, while an unfiled return leaves you exposed to the IRS filing a substitute return for you — one that claims no deductions, no credits, and the worst filing status.
Set up a payment plan to cut the penalty rate in half. If you filed on time as an individual and enter an approved installment agreement, the failure-to-pay rate drops from 0.5% to 0.25% per month for the months the agreement is in effect. You can apply online, and for balances under $50,000 the approval is largely automatic. Interest still accrues, but halving the penalty rate meaningfully slows the bleeding.
How to Get Penalties Removed
The IRS offers two main paths to penalty relief. They apply to penalties — rarely to interest — and you generally must be current on filing and payment (or on a payment plan) before either is granted.
First-Time Penalty Abatement: The Clean-Record Pass
First-Time Abatement (FTA) is an administrative waiver — no dramatic story required. If you qualify, the IRS removes failure-to-file, failure-to-pay, and failure-to-deposit penalties for one tax period, no questions about why you were late. The criteria:
- Clean compliance history. No penalties assessed (or all assessed penalties abated) for the three tax years before the penalty year. The estimated-tax penalty doesn't count against you.
- All required returns filed. Every currently required return must be filed, or a valid extension in place.
- Paid or arranged to pay. The balance for the penalty year must be paid in full or covered by an installment agreement.
FTA is available for individuals and businesses, and it can be requested by calling the IRS at the number on your notice or by mail. It's a use-it-wisely benefit: because it requires three clean years, think of it as a once-every-few-years reset, not an annual habit. If you have multiple penalty years, FTA typically applies to the earliest one, and reasonable cause (below) may cover the rest.
Reasonable Cause: When Circumstances Beat You
If you don't qualify for FTA, you can still request relief by showing the failure was due to reasonable cause and not willful neglect — that you exercised ordinary business care and prudence but couldn't comply anyway. Classic qualifying circumstances include:
- Death, serious illness, or unavoidable absence of the taxpayer or an immediate family member
- Fire, flood, natural disaster, or other casualty that destroyed records or made compliance impossible
- Reliance on incorrect written advice from the IRS or a competent tax professional (you must show you gave the adviser complete information)
- An inability to obtain records despite diligent efforts
What doesn't count: not knowing the rules, relying on an adviser to file without following up, or simply not having the money. Financial hardship alone is not reasonable cause for failing to file — though it can support a payment plan or other collection alternative.
To request reasonable-cause relief, call the number on your notice or write a letter explaining the facts, signing it under penalties of perjury and attaching supporting documents (hospital records, insurance claims, correspondence with advisers). You can also use Form 843, Claim for Refund and Request for Abatement, particularly to seek a refund of penalties you've already paid.
Keep Records That Prove Your Case
Whichever path you take, documentation wins. Keep copies of filed returns, proof of mailing or e-file acceptances, extension requests, payment confirmations, medical or disaster records, and any written advice you relied on. If your records live in a shoebox — or across five apps — reconstructing a timeline under deadline is miserable. Maintaining clean, complete books all year means that when you need to show the IRS exactly what happened and when, the evidence is already organized. A dashboard view of your accounts, like the visual reports in Fava, makes it easy to verify payment dates and balances before you pick up the phone.
Common Mistakes to Avoid
- Waiting to file until you can pay in full. The costliest mistake of all. File now, pay what you can, arrange the rest.
- Assuming an extension extends payment. It doesn't. Interest and the pay penalty run from April regardless.
- Paying the penalty without asking for relief. FTA is available by phone call for qualifying taxpayers, yet many people pay first and never ask. If penalties are already paid, Form 843 can still recover them within the refund limitations period.
- Requesting FTA when reasonable cause would serve better. FTA can only be used once per clean-history window and applies to one period; if you have one mildly late year and one catastrophic year, consider saving FTA strategy for where it helps most and arguing reasonable cause for the rest.
- Ignoring IRS notices. Every notice has a deadline, and silence escalates both enforcement and penalty rates. Open everything, calendar every date, and respond — or have your tax pro respond — before the clock runs out.
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