Tax Legal Services · Primary-source case analysis

Libitzky v. United States: A Timely Formal Refund Claim Could Not Cure an Expired Lookback Period

By Aneeta Mishra and Timothy Chan

Published April 20, 2026 · Updated October 18, 2026

Decision: Libitzky v. United States, No. 23-15614 (9th Cir. Aug. 5, 2024).

Libitzky illustrates how section 6511’s claim-filing deadline and amount-limiting lookback operate together even when the government agrees that the taxpayer overpaid.

A late return followed a substantial overpayment

The taxpayers overpaid nearly $700,000 for 2011 but did not file that return and a formal refund claim until January 2016. They had told the IRS in September 2015 that they intended to apply the overpayment.

Section 6511 imposes linked timing rules

A refund claim must satisfy section 6511(a), and section 6511(b)(2) separately limits recovery to tax paid within the applicable lookback period. The court included the six-month return-filing extension in the three-year lookback, producing a three-and-a-half-year window measured backward from January 20, 2016. The payment deemed made April 17, 2012 still fell outside it. The mistake was not failing to count the extension; even after counting it, no recoverable payment remained. Libitzky, opinion pages 4,12–14.

Formal and informal dates could not be mixed

Even assuming the September communication qualified as an informal claim, it preceded the return and therefore did not trigger the three-year filing framework. The taxpayers could not use the formal claim for subsection (a) and the informal date for a more favorable subsection (b) lookback.

Disposition

The court affirmed dismissal despite acknowledging the harsh result and the conceded overpayment. Statutory refund periods controlled notwithstanding reliance on an accountant who missed filing deadlines. The court also distinguished a timely defective claim later perfected from the taxpayers’ attempt to use a later return to cure an already untimely informal claim. This is the historical payment-and-filing record the court decided; disaster postponements or other current statutory exceptions require separate analysis.

Key takeaways

• Track both the claim deadline and the recoverable-payment lookback.
• Do not assume a timely claim makes every overpayment refundable.
• An informal claim cannot be used selectively to extend only one statutory period.
• Calendar refund deadlines independently of return-preparation arrangements.