The United States Postal Service (“USPS”) recently issued a final rule that became effective December 24, 2025 to clarify the definition and application of postmarks. The rule provides that a postmark applied at a USPS processing facility reflects the date of the first automated processing operation performed on a mailing, which may be one or more days after the date USPS actually took physical possession of the mail. This timing gap is expected to occur more frequently as USPS implements its Regional Transportation Optimization initiative and has important implications for employers sponsoring group health plans and retirement plans. Many participant notices, government filings, and contribution deadlines under ERISA and the Code are satisfied by “timely mailing” as proven by a postmark date. Importantly, Code Section 7502—commonly referred to as the “mailbox rule”—treats a document as timely filed if it bears a postmark on or before the filing deadline.
For plan sponsors, the potential lag between the date when mail is deposited at USPS and when it is actually processed and postmarked creates risk that time-sensitive materials (e.g., COBRA election notices, HIPAA certificates, decisions on benefit claims and appeals, summary plan descriptions, QDIA notices, fee disclosures and other required disclosures) may bear a postmark date later than intended, even if mailed before the deadline. Because compliance often hinges on demonstrating a timely postmark, plan sponsors and administrators should review current mailing procedures for any circumstances in which a missed deadline could result in penalties, excise taxes, or fiduciary liability.
To mitigate these risks, employers should consider operational changes such as mailing time-sensitive documents several days before deadlines, requesting a manual postmark from a clerk at a post office retail counter, obtaining a postage validation imprint label, or purchasing a Certificate of Mailing or using Certified Mail or Registered Mail for proof of mailing date. In addition, employers could also consider transitioning to electronic delivery methods where permissible to eliminate reliance on postmark timing altogether.
The USPS Final Rule can be found here.