USPS Rule Changes May Affect Tax Filing Deadlines, Warns National Taxpayer Advocate
As the 2026 tax filing deadline approaches, the National Taxpayer Advocate has issued a warning to Americans regarding recent changes to U.S. Postal Service (USPS) rules. These changes could result in mailed tax returns or payments being classified as late, even if taxpayers believe they sent them on time. The concern arises from new USPS procedures that affect how postmarks are applied. Previously, the 'timely mailed is timely filed' rule allowed taxpayers to rely on the postmark date as proof of timely filing. However, under the updated rules effective December 24, 2025, postmarks may now reflect the date mail is first processed at a postal facility, rather than the date it is placed in a mailbox or accepted locally. This change could lead to postmarks dated after the filing deadline, potentially resulting in penalties or interest for taxpayers.