USPS Postmark Changes: Impact on Filing and Payment Deadlines
Topics:
General Tax Guidance
Iowa law generally provides that tax returns, payments, and appeals mailed to the Iowa Department of Revenue through the United States Postal Service (USPS) are timely filed if postmarked on or before the due date of the return, payment, or appeal.
The USPS updated its Domestic Mail Manual, effective December 24, 2025. Postmarks are generally applied by the USPS via automation by machines at regional processing facilities. The date of a postmark applied at a processing facility may be one or more days after a mailed item is actually delivered to the USPS. Therefore, a return, payment, or appeal may be considered delinquent or untimely if mailed too close to a deadline, even if the return, payment, or appeal was placed in a mailbox before the deadline.
List items for USPS Postmark Changes
Customers should ensure that their returns and payments are timely by doing one of the following:
Mail your return and/or payment early. Mailing early reduces the chance that your envelope will receive a postmark date that is after the due date of the return or payment.
Go to a USPS retail location and ask for a manual postmark.
Hand delivery. Customers who are not mandated to file or pay electronically may drop off a return or payment at the Hoover State Office Building, 1305 E. Walnut St., First Floor, Des Moines, IA 50319.
The Iowa Department of Revenue is available to assist customers who want to learn how to file and pay electronically or otherwise have questions about this change.
