Beginning December 24, 2025, the United States Postal Service (USPS) quietly implemented significant updates to how postmarks are defined and applied. These changes directly affect taxpayers who plan to mail their tax returns and payments. If returns and payments are mailed on the due date, they will be considered late and subject to interest and penalties.

Historically, if taxpayers deposited their tax return in a mailbox or handed it to USPS on the due date, the postmark would reflect that day. This is no longer the case.

As a taxpayer, several key risks for you are:

  • Late filing penalties if a return or payment mailed on time is given a late postmark due to USPS routing delays.
  • No guarantee that a return or payment dropped in a mailbox on the deadline will receive that same-day postmark.
  • No consistent processing timeline, as mail may travel farther before postmark assignment.

What you should do:

  • E-filing and paying amounts due online are the safest and most predictable method for ensuring compliance.
  • Mail early, avoiding last minute filings altogether.
  • Use Certified Mail, Registered Mail, or a Certificate of Mailing for proof.

Bottom Line – Please adhere to the date that we ask you to get their information to us (February 15 for business returns and March 15 for individuals), e-file if at all possible, and pay amounts due online.

Please let us know if you have any questions.