Failure-to-File Penalty

The IRS failure-to-file penalty is 5 percent of the unpaid tax for each month or part of a month a return is late, and it keeps running until it reaches 25 percent. It accrues ten times faster than the penalty for paying late: a taxpayer who files five months late with a balance owing has already reached the ceiling on the filing side, while the same balance left unpaid on a timely return would have accrued 2.5 percent.

Whiteford's tax controversy attorneys represent individuals, businesses, estates, and partnerships with late-filed and unfiled returns, one of the IRS penalties we defend against most often. If you have received a penalty notice or you have returns you have not filed, schedule a confidential consultation with our tax team.

How the failure-to-file penalty is calculated

Internal Revenue Code section 6651(a)(1) sets the penalty at 5 percent of the amount required to be shown as tax on the return, for each month or fraction of a month the return is late, capped at 25 percent. A single day into a new month counts as a full month. A return due April 15 and filed May 16 has accrued two months of penalty, not one.

The base is the tax required to be shown on the return, not the total balance the IRS is chasing, so withholding and estimated payments already credited reduce the base before the percentage applies. Because of that, a late return reporting no tax due carries no percentage penalty at all, as the Federal Circuit held in Estate of Liftin v. United States, 754 F.3d 975 (Fed. Cir. 2014).

The minimum penalty for returns more than 60 days late

Once an income tax return is more than 60 days past its due date, including extensions, section 6651(a) imposes a floor. For returns required to be filed in 2026, the minimum is the lesser of $525 or 100 percent of the tax required to be shown on the return, rising to $535 for returns required to be filed in 2027. The floor matters most on small balances: someone who owed $400 and filed nine months late pays $400, not the $100 the 25 percent cap would otherwise produce.

How the failure-to-file and failure-to-pay penalties interact

Most delinquent filers owe both. Section 6651(c) keeps them from stacking at full rate: in any month both apply, the 5 percent failure-to-file rate is reduced by the 0.5 percent failure-to-pay rate, so the combined monthly charge stays at 5 percent. That offset does not continue past the five-month mark; once the failure-to-file penalty caps at 25 percent, the failure-to-pay penalty keeps accruing toward its own separate 25 percent ceiling.

An extension to file is not an extension to pay

A valid extension under section 6081 moves the prescribed filing date, so a taxpayer who files Form 4868 in April and files the return in September owes no failure-to-file penalty. Payment is a separate obligation: the section 6651(a)(2) failure-to-pay penalty runs from the original April due date regardless of the extension. Filing an extension and paying nothing eliminates the larger penalty and leaves the smaller one running, which is still the better outcome by a wide margin.

Fraudulent failure to file under section 6651(f)

When the IRS concludes the failure to file was fraudulent, section 6651(f) triples the rate: 5 percent per month becomes 15 percent, and the 25 percent cap becomes 75 percent. Three years of unfiled returns with substantial unreported income can carry a penalty approaching the size of the tax itself. The government bears the burden of proving fraud by clear and convincing evidence, a materially higher standard than the preponderance standard governing most civil tax disputes.

Reasonable cause and the Boyle rule

Section 6651(a)(1) excuses the penalty where the failure was due to reasonable cause and not willful neglect, requiring the taxpayer to show ordinary business care and prudence and an inability to file on time despite it. The Supreme Court narrowed what qualifies in United States v. Boyle, 469 U.S. 241 (1985): handing the file to an accountant who then misses the deadline is not reasonable cause, because the duty to file is fixed, clear, and belongs to the taxpayer.

Boyle preserved one distinction that still does real work. Reliance on an attorney's or accountant's substantive legal advice, including advice that no return was required at all, can constitute reasonable cause, while reliance on the same professional to perform the clerical act of transmitting the return cannot. The Eleventh Circuit confirmed in Lee v. United States, 84 F.4th 1271 (11th Cir. 2023), that Boyle governs e-filing too.

Claims that do succeed generally rest on circumstances outside the taxpayer's control, such as serious illness, a death in the family, destroyed records, or a federally declared disaster.

First-time abate and other relief paths

The IRS also grants relief that does not depend on reasonable cause. First-time abate removes the failure-to-file penalty for a taxpayer with a clean compliance history, generally meaning no penalty of the same type assessed in the three preceding tax years, all required returns filed or validly extended, and any tax paid or covered by an arrangement to pay. It is administrative policy rather than statute, so requesting it on the wrong year can spend the relief for less than it is worth.

Returns you never filed

The three-year assessment period in section 6501 runs from the date a return is filed, so until the taxpayer files, it never starts and older unfiled years stay open indefinitely. The IRS may prepare a substitute for return under section 6020(b), assembled from third-party information alone, allowing no itemized deductions, no basis in reported securities sales, and no business expenses, so the assessed liability routinely exceeds what an accurate return would show.

Filing an original return after a substitute assessment is often the fastest route to bringing the balance down. The Tax Court confirmed in Valentine v. Commissioner, T.C. Memo. 2022-42, that the section 6651(a)(2) failure-to-pay addition cannot be imposed on a non-filer unless the IRS first prepared a valid substitute for return.

Section 6751(b)(2)(A) also exempts every section 6651 addition to tax from the written supervisory approval requirement that defeats some accuracy-related penalties.

Why Whiteford

Michael March leads Whiteford's tax controversy and defense practice and handles civil and criminal tax matters before the IRS, the Department of Justice Tax Division, federal district courts, and the United States Tax Court. Late-filing penalty work sits across both halves of that practice: the civil penalty computation is mechanical, but the reason a return went unfiled usually is not, and that second question is where the exposure lives.

Our tax team works with delinquent filers across Maryland, Virginia, the District of Columbia, Delaware, New Jersey, New York, North Carolina, Florida, and Kentucky. A typical engagement involves reconstructing records for the open years, deciding how far back to file, and sequencing the filings so a first-time abate or reasonable cause request lands on the year where it is worth the most.