Failure-to-Pay Penalty

The failure-to-pay penalty is what the IRS adds to your bill when the tax you reported goes unpaid. It runs 0.5 percent of the unpaid balance for each month or part of a month the balance sits there, and it stops growing at 25 percent of the tax you owed. Interest runs alongside it on a separate track, which is why a balance that looked manageable in April can look very different two years later.

The penalty is not automatic in the sense of being final. It can be reduced, waived, or removed, and the route depends on which subsection the IRS assessed under and what your compliance history looks like. It is one of several IRS penalties Whiteford's tax controversy attorneys handle from the first notice through Appeals.

How the IRS calculates the failure-to-pay penalty

Section 6651(a)(2) of the Internal Revenue Code imposes 0.5 percent of the unpaid tax for each month or fraction of a month the tax shown on your return remains unpaid after the payment due date, capped at 25 percent in the aggregate. A fraction of a month counts as a full month, so a payment that arrives on the second day of a new month picks up the same 0.5 percent as one that arrives on the thirtieth.

The base is the net amount due, not the original tax. Under section 6651(b)(2), the IRS recomputes the figure each month, reducing it by any part of the tax paid before that month began. A return reporting $40,000 in tax with nothing paid accrues $200 per month, reaching the 25 percent ceiling of $10,000 after 50 months. If the taxpayer pays $15,000 in month seven, the monthly accrual drops to $125 from month eight forward.

When the penalty rate doubles or drops

Section 6651(d) raises the rate to 1 percent per month beginning the first month after the earlier of two events: ten days after the IRS issues a notice of intent to levy under section 6331(d), or the day the IRS demands immediate payment on a jeopardy assessment. The Internal Revenue Manual identifies the correspondence that triggers this, including a CP504 final notice, a Collection Due Process notification, an ACS Letter LT11, and a Field Collection Letter 1058, so treating one of those as ordinary mail doubles the monthly accrual.

Section 6651(h) cuts the rate to 0.25 percent per month for any month an installment agreement under section 6159 is in effect. The reduction applies only to individuals, not entities, and only if the return was filed by its due date, including extensions. An individual who filed late does not get the reduced rate even after the agreement is approved.

Filing late and paying late at the same time

The failure-to-file penalty under section 6651(a)(1) is ten times larger, at 5 percent per month up to 25 percent. When both apply in the same month, section 6651(c)(1) reduces the failure-to-file penalty by the failure-to-pay penalty assessed that month, so the combined exposure is 5 percent, not 5.5 percent. A return filed five months late with nothing paid hits the combined 25 percent ceiling at month five, which on a $40,000 balance is $10,000 in penalties before any interest.

Tax the IRS assessed that was not on your return

Section 6651(a)(3) covers amounts the IRS assessed that your return did not show, including math-error assessments under section 6213(b). The rate and 25 percent cap are the same, but the penalty begins only after you fail to pay within 21 calendar days of the notice and demand, shortened to 10 business days when the amount is $100,000 or more. The First Circuit's decision in Shafmaster v. United States confirms that a taxpayer contesting this penalty has to show inability to pay or undue hardship within that notice-and-demand window.

Interest on the tax and on the penalty

Interest under section 6601 accrues on unpaid tax at the underpayment rate set quarterly under section 6621, the federal short-term rate plus three percentage points, and compounds daily under section 6622. Interest on the failure-to-pay penalty itself accrues only if the penalty goes unpaid for 21 calendar days after notice and demand, and only from that date forward, unlike the failure-to-file penalty, where interest runs all the way back to the original return due date.

Grounds for removing the penalty

Section 6651(a) waives the penalty where the failure was due to reasonable cause and not willful neglect. For late payment, Treasury Regulation 301.6651-1(c)(1) requires a two-part showing: the taxpayer exercised ordinary business care and prudence in providing for payment, and was nevertheless unable to pay or would have suffered undue hardship. The statement has to be affirmative, in writing, and made under penalty of perjury.

Inability to pay by itself does not carry the argument. The Court of Federal Claims held in Christman v. United States that inability to pay on time is insufficient without a showing of business care and prudence in planning for the liability, and the regulation is explicit that lavish spending or speculative investments made at the expense of the tax obligation defeat the claim.

First-time abate

First-time abate is an administrative waiver under the Internal Revenue Manual, reaching the failure-to-pay penalty under both section 6651(a)(2) and section 6651(a)(3). It requires a clean compliance history: returns filed and taxes paid or arranged for the prior three years, with none of the covered penalties assessed. The Manual directs the IRS to consider the waiver before reasonable cause, but it is not enforceable in court, as the district court held in Intress v. United States.

An extension to file is not an extension to pay

An extension granted under section 6081 extends the filing deadline only, so a filing extension alone leaves the penalty running from the original due date. Under Treasury Regulation 301.6651-1(c)(3), an individual who obtains an automatic filing extension is presumed to have reasonable cause for the extension period if the shortfall between the tax shown and the amount paid by the regular due date is no more than 10 percent of the tax shown, with the balance remitted with the return.

Corporations have a parallel 90 percent rule tied to Form 7004.

How to request abatement or a refund

If the penalty is assessed but unpaid, the request goes to the IRS in writing, establishing First-Time Abate eligibility or reasonable cause. If the penalty has already been paid, the vehicle is Form 843, Claim for Refund and Request for Abatement. District court and the Court of Federal Claims generally require full payment and a refund claim first.

A Collection Due Process hearing under section 6320 or 6330 is often the better route: it allows a challenge to the underlying liability with no prepayment required, and the determination is reviewable in Tax Court.

Why Whiteford

Michael March handles tax controversy and defense work for Whiteford and takes calls from taxpayers directly. The practice covers IRS examinations, Appeals, collection matters including liens and levies, and criminal tax defense, which matters on a late-payment file because the facts that support a hardship argument are frequently the same facts that need careful handling if the exam turns.

Whiteford is admitted in Maryland, the District of Columbia, Virginia, Delaware, New Jersey, New York, North Carolina, Florida, and Kentucky, with tax controversy work handled out of Baltimore, Washington, Columbia, Towson, Wilmington, Richmond, Virginia Beach, and Fairfield.

Where a penalty file is worth defending, the work is usually documentary: reconstructing what the taxpayer knew, what was in the account, and what was done about it in the weeks before the due date.