USPS Clarifies Postmark Rules, Raising Deadline Risks for Tax Filers, Voters, and Businesses

Overview

• A final rule effective December 24, 2025 (Section 608.11) states that many postmarks reflect the date of first automated processing rather than the day USPS first took possession.
• USPS characterizes the change as a clarification and notes its Regional Transportation Optimization will make acceptance-to-postmark gaps more common.
• Because tax filings under Internal Revenue Code section 7502 rely on postmark dates, legal advisors recommend Certified Mail, Priority Express, or IRS‑approved private delivery services to document timely mailing.
• Senders can request a manual hand-stamped postmark at a retail counter or buy a Certificate of Mailing to create contemporaneous proof of the mailing date.
• Local election officials, including in Bexar County, advise mailing earlier and retaining certified mail receipts, and businesses are urged to review contract notice provisions and allow alternative delivery methods.