The U.S. Postal Service changed how postmark dates are applied late in 2025. It’s a small change with potentially big implications for anyone who mails time-sensitive information — like tax documents.
What changed
- Under the new rule, a machine-applied postmark now reflects the date of the “first automated processing operation,” not necessarily the day the mail was dropped off.
- That processing date could be later than when the item actually entered the postal system.
Why it matters
- For tax documents and payments that have to follow the “timely filed” rules, the postmark date matters.
- If the IRS receives a filing after the deadline and the postmark shows a later date, it may not be considered timely, even if it was mailed earlier.
- With the government ending paper checks, this might be less of an issue. But there are likely other documents that taxpayers might still mail.
How to protect yourself
- Request a manual postmark by handing your envelope directly to a USPS retail counter employee.
- Use the USPS postage validation imprint, which shows the official acceptance date when you buy at the counter.
- Consider certified or registered mail and keep the receipt as proof of the mailing date.
If mailing deadlines matter for you, taking one extra step at the post office can help avoid unnecessary headaches later.
If you have questions about your taxes, payments, or deadlines, let us know.