USPS New Postmark Rule Could Impact Your Tax Return Filing
As of December 24, 2025, the USPS updated its Domestic Mail Manual (DMM 608.11) to stipulate that postmarks reflect when mail is first processed at a regional facility, not when it was deposited with the Postal Service. This change means a tax return dropped on April 15 may not be postmarked until April 16 or later, risking penalties.
Key Changes and Impact:
Processing Date vs. Deposit Date: The postmark now reflects the date of the first automated processing operation at a sorting facility, not the day it was dropped in a mailbox.
Regional Delays: Due to infrastructure consolidation, mail can take days to reach processing centers, causing the postmark to lag behind the physical mailing date.
Tax Return Consequences: Because the IRS relies on the postmark date for timely filing (IRC §7502), a return mailed on April 15 could be considered late if the postmark is dated for the following day.
How to Ensure Timely Filing:
Use Hand-Cancellation: Go to a post office retail counter and request a hand-stamped postmark to confirm the actual mailing date.
Mail Early: Submit tax returns several days before the deadline to accommodate processing delays.
Use Certified Mail: Use certified mail to create a legal record of mailing that can be used to prove timely filing even if the postmark is delayed.
