Postal Service Rule for Postmark Dates

On December 24, 2025, The U.S. Postal Service finalized a ruling in relation to postal possession and postmarks. The rule recognizes markings that qualify as postmarks, outlines marking application conditions, and illustrates how consumers can document USPS mailing procedures.

The rule clarifies that USPS postmarks mail on the date it is received at a postal facility, which may be later than the date a taxpayer drops off or submits the mail. A postmark shows when USPS had possession of the mail, but it does not necessarily reflect the date USPS first accepted it. This matters for taxpayers relying on the “timely mailing, timely filing” rule under Section 7502 (the mailbox rule), which generally treats a paper return or payment as filed on time if it is properly addressed, postmarked by the due date, and delivered—even if it arrives late.

To protect themselves, taxpayers who need proof of a specific mailing date should request a manual (local) postmark at the post office when they mail an item or use services such as certified mail and retain the receipt. Pre-printed postage labels alone only show when postage was purchased and do not prove when USPS accepted the mail.

What taxpayers should do:

• Mail time-sensitive items early.
• Request a manual postmark when deadlines matter.
• Use certified mail and keep receipts.
• Do not rely solely on pre-printed postage labels.