Important Mailing Reminder:
Effective December 24, 2025, the United States Postal Service has implemented changes that may affect the postmark date, and that date may now be later than the date an item is dropped in the mail. Because tax deadlines are based on the postmark date, mailing close to a deadline may result in a late postmark. Obtaining proof of mailing, such as a manual USPS postmark obtained at a retail counter; Certificate of Mailing; or sending by Certified Mail, Registered Mail, or another IRS-approved delivery service that provides documented proof of mailing date can help reduce this risk.
Recent changes implemented by the United States Postal Service (“USPS”) may affect the postmark dates applied to mailed tax returns, payments, and other time-sensitive correspondence.
Electronic filing and electronic payment remain the most reliable methods for timely submission and confirmation. If mailing is necessary, you may wish to obtain proof of mailing, such as a manual USPS postmark obtained at a retail counter; Certificate of Mailing; or sending by Certified Mail, Registered Mail, or another IRS-approved delivery service that provides documented proof of mailing date.
Background:
Effective December 24, 2025, USPS adopted a final rule adding Section 608.11 to the Domestic Mail Manual regarding USPS postmarks. Machine-applied postmarks will generally reflect the date mail is first processed at a regional USPS processing facility, rather than the date an item is deposited at a local post office or mailbox.
As a result of changes in USPS procedures impacting postmark dates, the postmark date on mailed items may be applied days after the item is delivered to USPS. This may cause a return, payment, or other submission that was mailed on or before a statutory deadline to nevertheless receive a postmark dated after the due date.
Because federal and state tax filing deadlines are determined by the postmark date (not the date of deposit), these changes introduce new timing risks for filings and payments submitted by mail across all jurisdictions.
Under current USPS processing procedures, routine mailbox drop-off, including at after-hours post office slots, may no longer reliably produce a same-day postmark.
For additional information refer to the USPS Postmarking Myths and Facts.