Tax Tip #290

The U.S. Postal Service (USPS) changed how postmark dates are determined. This update could impact anyone mailing time-sensitive documents like tax returns.

Old Rule: The postmark usually reflects the date you drop your mail in a USPS mailbox or at the post office. 

New Rule effective December 24, 2025: The postmark will now show the date your envelope is first processed by an automated USPS sorting machine. This could be later than the day you mailed it. 

Example: Taxpayer drops a tax return in a blue collection box at 6PM on April 15 (Tax Day). USPS picks up the mail that night but doesn’t process it until April 16. Under the new rule, the postmark will read April 16. Result: Late filing penalty, even though it was mailed timely. 

Solutions to avoid potential late filing penalties:

• Go to the counter & request a manual/hand-stamped postmark at the post office showing the actual mailing date.
• Buy postage at the counter. The printed label includes the correct acceptance date.
• Use Certified or Registered Mail. These services provide a receipt with the mailing date as proof.
• Better yet, e-file on or before the due date.