Missing a filing deadline is not a catastrophe. It is also not free. The cost depends on what you did, what you owe, and how quickly you respond.

This post is about a single missed deadline or a recent late filing. If you have multiple years of unfiled returns, the unfiled-returns post is the better starting point. The framing here is for the filer who missed the April 15 deadline, did not file an extension, and needs to know what happens next.

The two penalties (and why people confuse them)

The IRS imposes two separate penalties for late tax compliance. Most people mix them up. The math is different.

Failure to file. This applies when you do not submit a return by the deadline (including extensions). The penalty is 5% of the unpaid tax for each month or partial month the return is late, up to a maximum of 25%. If the return is more than 60 days late, the minimum penalty is the lesser of $510 (for 2025 returns) or 100% of the unpaid tax.

Failure to pay. This applies when you do not pay the tax owed by the deadline (regardless of whether you filed). The penalty is 0.5% of the unpaid tax per month, up to 25%.

When both penalties apply to the same month, the failure-to-file penalty is reduced by the failure-to-pay amount, so the combined monthly rate is 5% rather than 5.5%. Interest accrues separately on both penalties and on the unpaid tax balance, at the federal short-term rate plus 3%, compounded daily.

The structure is deliberate. Failure to file is ten times more expensive per month than failure to pay. The IRS wants returns filed even if the tax cannot be paid immediately.

The first-day rule

Once the return is filed, the failure-to-file penalty stops accruing. The failure-to-pay penalty continues until the balance is paid.

This is the most important fact in this post. If you missed the deadline and you owe tax, file the return today. Even an unpaid return stops the larger penalty from compounding.

Filers regularly delay submitting a late return because they cannot afford the balance. That instinct is wrong. The cost of not filing while you figure out the payment is much higher than the cost of filing first and arranging payment afterward.

If the return is straightforward, file it. If it is complicated and would benefit from professional preparation, file what you can to stop the penalty clock and arrange a payment plan or abatement separately.

First-Time Penalty Abatement

The IRS offers a first-time penalty abatement (FTA) program that can remove failure-to-file, failure-to-pay, and failure-to-deposit penalties for one year if you meet three conditions:

1. Filing compliance. You have filed (or filed an extension for) all currently required returns.
2. Payment compliance. You have paid, or arranged to pay, any tax due.
3. Clean three-year history. No penalties were assessed in the prior three years (with limited exceptions for estimated tax penalties).

FTA is generous. It applies whether or not you have a “good reason” for the late filing. The IRS has internal procedures that grant it authority to administratively qualify cases.

It is also a one-time benefit. Use it strategically. If you have multiple years of penalties, applying FTA to the year with the largest penalty produces the most benefit.

Reasonable cause

If FTA is unavailable (due to a prior penalty within the last 3 years), reasonable cause is the next path.

Reasonable cause requires showing that the late filing was due to circumstances beyond your control, despite ordinary business care and prudence. The IRS evaluates each case on the specific facts. Documented examples that have been accepted include:

• Serious illness or death in the immediate family
• Casualty (fire, flood, natural disaster) affecting records
• Inability to obtain records despite reasonable efforts
• Reliance on incorrect written advice from the IRS or a competent tax advisor

What is not reasonable cause: forgetting, being too busy, financial difficulty (this can reduce failure-to-pay penalties but not failure-to-file), or relying on incorrect information from your preparer’s office staff.

Reasonable cause requests are made on Form 843 or in written correspondence with the IRS. Documentation matters. A request without supporting evidence is much less likely to succeed.

Extensions: what they do and what they do not

A timely extension (Form 4868 for individuals, filed by April 15) extends the filing deadline to October 15. It does not extend the payment deadline.

This is the most common misunderstanding about extensions. An extension means failure to file is not in play. It does not pause failure-to-pay. If you owed $40,000 on April 15, and you filed an extension and paid nothing, you accrue 0.5% per month (plus interest) on that $40,000 from April 15 forward. Over six months, that is 3% plus interest, on top of the original balance.

The strategic use of extensions is to get the filing right while paying an estimated balance forward. The extension protects against failure-to-file. The estimated payment protects against failure-to-pay.

State-level differences

For DMV filers, the federal penalty structure is the floor. Each state has its own.

DC, Maryland, and Virginia each have late-filing and late-payment penalties that apply on top of the federal penalties, with their own rates and abatement rules. The specifics change with state legislation, so the rates should be confirmed at filing rather than memorized. Maryland and Virginia have first-time-abatement equivalents with different mechanics; DC handles abatement on a case-by-case basis.

The practical implication for a DMV filer: a missed federal deadline is also a missed state deadline, and the cleanup work has to address both.

When professional help is right

For a single missed deadline with a manageable balance, a competent self-prepared return plus a payment plan (Form 9465) is usually adequate.

Professional help becomes valuable when:

• You have multiple years of late filings (different post)
• The balance is large enough that abatement is worth pursuing seriously
• You are also dealing with an audit, lien, or collection action
• The return is complex enough that filing it incorrectly creates worse problems than the original lateness

The cost of poorly handled late filings shows up months or years later, usually as a state notice or a federal collection action. Earlier engagement is almost always cheaper than later cleanup.

What to do next

If you missed the deadline, file the return as soon as possible to stop the failure-to-file penalty. If the situation is more complicated than that, book a complimentary 15-minute strategy call to walk through your options.