PSA: Changes In U.S. Post Office Rule Affect Date Sensitive Mail

There’s a change in U.S. Post Office rules that went into effect on December 24, 2025 that will affect anyone who needs to drop a date sensitive item in the mail. If you use what is now commonly referred to as “snail mail,” think taxes. Think donations that you make the end of the year. Think normal bill paying.

We’ve been accustomed to what was a time honored legal tradition that if we dropped that bill in the mailbox or at a post office that it was postmarked that day and the postmark would be honored when it was received. When it comes to end of the year donations and ordinary bill paying the “mailbox rule” was honored as the date that should be credited or accepted. Well, that’s no longer necessarily the case.

Again, think of every news story you’ve ever read about long lines of last minute tax filers at a post office on April 15th. The new rule doesn’t actually change when an item is postmarked but it clarifies that a machine-applied post mark represents “the date of the first automated processing operation” at a processing facility rather than the date the piece of mail was dropped off. In USPS speak:

…while a postmark confirms the USPS possessed a mail piece on the date inscribed, that date does not necessarily align with the date the USPS first accepted possession of the item.

So, if you drop off mail in the box in front of your post office don’t count on it being post marked if you beat the pickup time marked on the box. If you do a search on this change you’ll see plenty of links from accounting firms alongside local municipalities giving a heads up to clients and local citizens.

There is a remedy for customers who need something post marked on a specific date. You can go to a post office and request a manual postmark, or when you pay for postage at a retail counter the machine label affixed by the post office also indicates the date. Of course you could also pay for Registered or Certified Mail and keep the receipt as evidence.

(Image from Jonathan Weiss on Shutterstock)

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