Wait a Minute, Mr. Postman!
The United States Postal Service added a new section to the Domestic Mail Manual (DMM) in late 2025. Why, you may be asking, is this in a tax blog? Why would we care what the USPS has in its Mail Manual?
The new section 608.11 defines postmarks, gives detailed information about what qualifies as a postmark, and, most importantly, describes when exactly those postmarks are applied.
Stamp of Approval
So what exactly does a postmark mean? It means that the Postal Service accepted custody of a piece of mail and was in possession of it at the time the mark was applied. Postmarks are applied when items are processed, either by an automated operation or manually at a retail location. In the past, mail was picked up from drop-off locations and processed on the same day, so the postmark generally matched the date the item was dropped off.
The new language in the DMM, as detailed in 39 CFR Part 111, doesn’t change any rules; it simply clarifies to the public the relationship between the postmark and the date of mailing. What is changing is the timeline for moving mail from the drop-off locations to the processing facilities. Because of these changes to the transportation operations, some mailed items will have postmarks that are a day or two later than the actual mailing date.
Signed, Sealed, Delivered?
Under Internal Revenue Code §7502(a), a tax return or payment is considered timely filed if the date of the postmark is on or before the due date. The changes to the postmark process mean that our clients might drop their payments or returns in the mail on April 15th, but find themselves saddled with failure-to-pay or failure-to-file penalties because the postmark wasn’t applied until a day or two later.
These problems are avoided entirely by filing and paying electronically, but when electronic methods aren’t an option, relying on the postmark to save you won’t be enough.
Best practice has been, and remains, to send all correspondence to the IRS via certified mail. Once that certified stamp is applied, the item is treated as if it were placed directly in the hands of the IRS on that date, providing proof not only of timely mailing but also of delivery.
Individuals who opt not to pay for certified or registered mail can go to the Post Office and request a manual postmark on their mail. But if you’re going in anyway…
Post Haste
While this may seem like much ado about nothing, helping clients understand the meaning of these changes and encouraging them to utilize electronic options and, if necessary, certified or registered mail may save headaches and money in the long run.