Representation before the IRS · Related issues

Statute of limitations: assessment, refund, and collection

Federal tax has three separate clocks, and most limitations mistakes come from mixing them up. The assessment clock limits how long the IRS has to determine and record additional tax. The refund clock limits how long a taxpayer has to claim money back. The collection clock limits how long the IRS has to collect tax once it is assessed. Each starts from a different event, each has its own extensions and suspensions, and a case can be open on one clock and closed on another.

The rule

Assessment. The IRS must assess tax within three years after the return was filed (IRC § 6501(a)). A return filed before its due date is treated as filed on the due date (IRC § 6501(b)(1); § 6513(a)), so early filing never shortens the period; late filing pushes the start to the actual filing date. Two important exceptions extend it: where the return omits an amount of gross income exceeding 25 percent of the gross income stated on it, the period is six years, as it is for an omission over $5,000^TY2026 attributable to a foreign asset reportable under § 6038D (IRC § 6501(e)(1)(A)(i), (ii)); and where no return is filed, or the return is false or fraudulent with intent to evade tax, there is no limitations period at all (IRC § 6501(c)(1)–(3)). The three-year period is measured to the date the IRS records the assessment, not the date it sends a notice, and a statutory notice of deficiency issued before the period ends suspends it while the taxpayer can petition the Tax Court and for 60 days after (IRC § 6503(a)(1)).

Refund. A claim for credit or refund must be filed within three years from the time the return was filed or two years from the time the tax was paid, whichever is later; if no return was filed, the two-year rule applies (IRC § 6511(a)). Timely filing is only half of it. The amount refundable is capped by the look-back: for a claim filed within the three-year window, the refund cannot exceed tax paid within the three years (plus any extension period) immediately before the claim; for a claim under the two-year rule, only tax paid within the two years before the claim (IRC § 6511(b)(2)). Withholding and estimated payments are deemed paid on the original due date of the return (IRC § 6513(b)), which is why a taxpayer who files a delinquent return four years late usually gets nothing back even though the return itself is the “claim.” Two categories of claim get longer periods, and both are easy to miss: a claim arising from a debt that became worthless or a security that became worthless runs seven years from the due date of the return for the year involved (IRC § 6511(d)(1)), and a claim attributable to foreign taxes paid or accrued for which a credit is allowed runs ten years from the due date of the return for the year those taxes were paid or accrued (IRC § 6511(d)(3)(A)). In both, the statute expressly allows the refund to exceed what the ordinary look-back would permit. Separately, the IRS may disregard a period of up to one year for a taxpayer affected by a federally declared disaster, a significant fire, or a terroristic or military action, which postpones the deadline for filing a claim (IRC § 7508A(a)).

Collection. Once tax is assessed, the IRS has ten years to collect by levy or by a court proceeding (IRC § 6502(a)(1)). This is the collection statute expiration date, or CSED, and it can be suspended or extended by several events discussed below.

Periods at a glance

How it works in practice

The IRS tracks the assessment statute expiration date (ASED) on every return and will not open or continue an examination that cannot be closed before it runs, which is why an examiner working a return near the end of the third year will ask the taxpayer to sign Form 872, a consent that extends the assessment period to a specified date (IRC § 6501(c)(4)). The consent must be signed before the existing period expires; a consent signed afterward is void. Form 872-A is an open-ended version terminated by Form 872-T. A taxpayer may refuse; the practical result is that the IRS issues a notice of deficiency for whatever it can support at that point.

For refunds, the claim is normally the amended return, Form 1040-X for individuals, or Form 843 for penalties, interest, and certain other taxes. The two dates that matter are the postmark date of the claim and the dates the tax was paid. If the IRS disallows the claim, the taxpayer has two years from the notice of disallowance to sue in district court or the Court of Federal Claims (IRC § 6532(a)(1)); the taxpayer may also sue after six months if the IRS has not acted.

For collection, the CSED runs from each assessment separately, so a single tax year can have several CSEDs: the original assessment, a later exam assessment, and a penalty assessment each start their own ten years. The period is suspended while the IRS is legally barred from collecting and, in most of those situations, for a tail afterward.

The offer-in-compromise and installment-agreement suspensions work through the levy bar rather than directly. Section 6331(k) prohibits levy while an offer is pending and for 30 days after rejection, plus any appeal filed in those 30 days, and likewise while a proposed installment agreement is pending, for 30 days after rejection or termination, and during an appeal (IRC § 6331(k)(1), (k)(2)). Section 6331(k)(3)(B) then applies rules similar to § 6331(i)(5), which suspends the § 6502 period for as long as the levy bar is in force. The exception is the one practitioners get wrong: § 6331(k)(3)(B) expressly carves out paragraph (2)(C), the period during which an installment agreement is in effect. So an agreement in good standing bars levy without stopping the clock, while the weeks spent waiting for a decision on it do stop the clock.

The other suspensions are direct. A Collection Due Process hearing suspends the period while the hearing and any appeals are pending, and — a floor that is easy to overlook — the period cannot expire before the 90th day after the final determination (IRC § 6330(e)(1)). Bankruptcy suspends it while the IRS is barred from collecting and for six months after (IRC § 6503(h)). Absence from the United States for a continuous period of at least six months suspends it, and if fewer than six months remain when the taxpayer returns, the period runs to six months after the return (IRC § 6503(c)). Voluntary extensions of the collection period are limited to those made in connection with an installment agreement (IRC § 6502(a)(2)).

Currently not collectible is not on that list. Reporting an account as currently not collectible is an administrative decision to stop active collection, not a legal bar to it: no provision of § 6503 or § 6331 suspends the period, and the Internal Revenue Manual treats a currently-not-collectible module’s CSED as continuing to run, which is why such accounts are eventually closed by statute expiration rather than by payment (IRM 5.16.1).

How this has changed

The three-year assessment rule and the ten-year collection rule are long-standing, but the collection period has been reshaped over time. Before 1990 the collection period was six years; the Omnibus Budget Reconciliation Act of 1990 made it ten. The IRS Restructuring and Reform Act of 1998 removed the IRS’s practice of obtaining open-ended waivers of the collection period from taxpayers, restricting extensions to those tied to installment agreements, and added the Collection Due Process suspension. More recently, the Supreme Court in United States v. Home Concrete & Supply, LLC (2012) held that an overstatement of basis is not an “omission from gross income” for the six-year rule; Congress responded in the Surface Transportation and Veterans Health Care Choice Improvement Act of 2015 by amending § 6501(e)(1)(B) so that an overstatement of unrecovered cost or basis is an omission for this purpose. Any legislation after the tax year shown in the verification stamp has not been incorporated.

Exam focus

Part 3 questions on this outline item almost always test one of four things: measuring the three-year assessment period from a return filed early or late; the six-year and unlimited exceptions and what triggers each; the refund rule with its look-back, especially the delinquent filer who gets nothing back; and events that suspend the ten-year collection period. Expect date arithmetic; write out the timeline before choosing an answer.

Check yourself

1. A taxpayer files a 2024 return on March 3, 2025. Absent an extension or exception, the last day for the IRS to assess additional tax is: (A) March 3, 2028 (B) April 15, 2028 (C) March 3, 2031 (D) April 15, 2031 Answer: B. An early-filed return is deemed filed on the due date; three years from April 15, 2025.

2. A taxpayer files a 2021 return on May 1, 2026 with $3,000 of withholding and no other payments. The maximum refund is: (A) $3,000 (B) $2,000 (C) $0 (D) It depends on the tax due Answer: C. Withholding is deemed paid April 18, 2022, outside the three-year look-back from May 1, 2026.

3. Which event does NOT suspend the ten-year collection period? (A) A pending offer in compromise (B) An accepted installment agreement in good standing (C) A pending Collection Due Process hearing (D) The taxpayer’s bankruptcy case Answer: B. An installment agreement suspends the period only while it is pending or being appealed after rejection, not while it is in effect.