New IRS Rule re: USPS Proof of Delivery

In summary, TAXPAYERS CAN NO LONGER RELY ON THE POSTMARK DATE AS PROOF OF DELIVERY DATE TO THE POSTAL SERVICE.

The United States Postal Service (“Postal Service”) has adopted a new rule, Section 608.11, which adds “Postmarks and Postal Possession” to the Domestic Mail Manual. The definition of “postmark” provides that it may be placed on a mailpiece at a retail location (e.g., local postal office) or at the regional processing center. However, other provisions of the rule indicate that, by default, the postmark will be applied at the regional processing center unless a customer requests the local postal office to manually apply the postmark on a mailpiece at the time of presentation. The rule will take effect on December 25, 2025.

The postmark policy change could affect the timeliness of tax reports and returns, which have a due date that is based on the postmark date. Because a regional processing center will apply the postmark, the inscribed postmark date may not align with the date on which the Postal Service first accepted possession of the mailpiece from a taxpayer. This means TAXPAYERS CAN NO LONGER RELY ON THE POSTMARK DATE AS PROOF OF DELIVERY DATE TO THE POSTAL SERVICE.

The federal rule provides that taxpayers may do one of the following if they want a postmark aligning with the date on which the Postal Service first accepted possession of their mail:

· Request a postmark be manually applied at the time of presentation of the mail piece to the local postal office.

· Contact the local postal office in advance to make arrangements if 50 or more mailpieces will be presented for manual postmark application to ensure that adequate resources are available.

· Purchase a Certificate of Mailing for an additional fee, which is a service that provides proof that individual mailpieces have been submitted for mailing.

The rule further states that pre-printed labels applied by a customer before mailing, such as postage from self-service kiosks or meter strips, only show that the customer purchased postage on the printed date. However, they DO NOT confirm the acceptance of the mail by the Postal Service, nor the specific date on which such acceptance occurred.

FR 2025-20740 published in the Federal Register on November 24, 2025.