A new postmark rule for the United States Postal Service took effect on December 24, 2025. The USPS postmark is an official mark that shows where and when mail was accepted by the Postal Service. Previously, when you dropped mail in a mailbox or blue postal box, you could assume that mail would be postmarked on the day you dropped it in the box—when you mailed it. With the new rule now in place, postmarks for mailboxes or blue postal boxes will be applied at regional sorting facilities when the processing begins, which could potentially be up to a few days after you mailed the item. This means tax payments, charitable contributions, legal filings, rent payments and other bills or items that rely on postmark dates for deadlines may be impacted by these later postmarks and late fees, penalties, or delinquency could now apply.
To avoid the potential of late postmarks on time sensitive mail, it is recommended you go inside your local post office and ask for a hand-stamped postmark for the date you are mailing, or plan accordingly and put this type of mail in the mail several days before a deadline if feasible. We also recommend sending time sensitive tax filings via certified mail to properly document the date and receive confirmation once delivered.
