03/18/2026
As tax season gets underway, the U.S. Postal Service has updated how postmarks are applied — and that change could matter for time-sensitive mail.
Under the revised process, some mail pieces may receive a postmark based on when they’re processed by USPS, rather than the date they’re dropped off or collected. For documents where the postmark date determines whether something was submitted on time, this distinction can be important.
That includes items such as:
➡️ Tax returns and supporting documents
➡️ Estimated tax payments
➡️ Requests for extensions
➡️ Other official forms or correspondence tied to filing deadlines
With this change in mind, allow extra mailing time. You may want to confirm which electronic or in-person submission options will help reduce last-minute issues during a busy filing season.
Source:
Dates on mail now reflect when it’s processed, not when it’s dropped off
