Lindabury, McCormick, Estabrook & Cooper, P.C. Firm News & Events
On November 24, 2025, the U.S. Postal Service (“USPS”) finalized a rule regarding when and how postmarks are applied. See 39 C.F.R. § 111 (2025). It is important for taxpayers and their advisors to be aware of the change because it has an impact on proving that a document was filed. While the rule does not change how mail is processed, it does change how postmarks should be understood, especially when deadlines matter.
What Changed?
While postmarks have long been relied upon as evidence that a document was mailed on a certain date, the new rule makes clear that this assumption is not always accurate. In most cases, postmarks are applied by automated machines at regional processing facilities, and not at the local post office where a piece of mail is dropped off. As a result, the date printed on a postmark may reflect the date the piece was first processed—not the date it was actually placed in the mail or collected by the USPS.
The rule also clarifies that only a manual, local postmark—which may be requested at the retail counter of a post office—reflects the actual date USPS accepted the item for mailing. When definitive proof of mailing on a specific date is needed, USPS advises using services such as Certified Mail or Registered Mail.
Why This Matters
Many tax-related actions depend on strict deadlines or proof of timely compliance. Common examples include the filing of Federal Estate Tax returns and New Jersey Inheritance Tax returns, federal and state income tax returns, elections made after a death for tax purposes, and deadline-driven correspondence with courts and beneficiaries. It had long been the case that postmarks on tax returns constituted proof of mailing on the date of the postmark. Indeed, this rule is set forth in the Internal Revenue Code. I.R.C. § 7502. Now, however, the postmark no longer provides reliable proof of compliance with a filing deadline.
Practical Guidance
Taxpayers should not rely on automated postmarks to prove the filing of time-sensitive documents. When mailing documents close to a deadline, request a manual, local postmark at the post office counter or use Certified Mail, Registered Mail, or a Certificate of Mailing to create a clear record. Whenever possible, send critical documents well in advance of deadlines. In some cases, hand delivery, private courier services such as Federal Express or UPS, or electronic filing when permitted, may be a safer option.