Tax Alert: New USPS postmark rule- Effective December 24, 2025

The U.S. Postal Service has changed how postmark dates are applied.  Postmarks no longer reliably show the date you mailed an item. Instead, they usually reflect the date the mail is first processed at a USPS facility, which may be days after drop-off.

                                                                                                                Why This Matters for Taxes

The IRS and many state and local tax agencies (including Pennsylvania jurisdictions) rely on the postmark date to determine whether tax returns, payments, and extensions are filed on time.  A delayed postmark could result in penalties, interest, and denied extensions—even if you mailed it before the deadline.

Due to the high volume of outgoing mail leading up to filing and payment deadlines, MPB cannot guarantee that mailings will be postmarked by the due date and cannot take responsibility for late postmarks that result in penalties or interest. 

                                                                                                                 How to Protect Yourself

E-file and e-pay whenever possible (strongly recommended)

If mailing is necessary:

Go to the post office counter and request a manual postmark

Use Certified or Registered Mail

Obtain a Certificate of Mailing

Mail well in advance of deadlines

If you have questions about the best way to file or pay, please contact our office.