Please Mister Postman: New Postmark Rules May Complicate Filing Deadlines

Effective December 24, 2025, the United States Postal Service ("USPS") finalized new regulations governing postmarks "clarifying" that postmarks are not necessarily indicative of the date an item was mailed or received by the Postal Service. While this clarification may affect how postmarks are treated in areas from mail-in ballots to the "mailbox rule" under contract law, it also bears on an important feature of tax procedure: the "postmark rule" of Section 7502 of the Internal Revenue Code.

The Internal Revenue Code prescribes myriad deadlines for filing items with the IRS, including not only annual income tax returns (famously due on April 15 for individuals) but also numerous other information returns, election notices and other documents that must be timely filed in order to be effective or to avoid penalties. Ordinarily, these documents are deemed filed on the date they are actually delivered to the IRS. Under Section 7502, however, an item mailed by U.S.