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Illinois Warns of Postal Changes Affecting Tax Deadline
IDOR urges taxpayers to file early or request manual postmarks to ensure on-time delivery.
Apr. 12, 2026 at 2:37pm
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As the tax filing deadline approaches, Illinois officials warn of postal service changes that could impact timely mail delivery of returns.Springfield TodayThe Illinois Department of Revenue is warning taxpayers that recent changes to U.S. Postal Service postmark procedures could affect the timely delivery of state tax returns and payments mailed close to the April 15 deadline. IDOR Director David Harris is encouraging residents to file electronically or allow extra time for physical mail delivery, and to request manual postmarks if mailing returns at the last minute.
Why it matters
The new USPS postmark policy means the date printed on envelopes may no longer reflect when mail was actually dropped off, potentially causing issues for taxpayers trying to meet the filing deadline. This could lead to penalties or delays for those who cut it close when mailing returns.
The details
Under the updated USPS procedures, postmarks will continue to show the date of first automated processing, but may no longer indicate the physical drop-off date at a local post office. To ensure on-time delivery, IDOR is advising taxpayers to file electronically or mail returns well before the April 15 deadline. Taxpayers can also request a manual postmark at any USPS retail location, which will reflect the date the postal service took physical possession of the mail.
- The April 15 filing deadline applies to most Illinois individual income tax returns.
- IDOR issued the warning about postal changes this week.
The players
Illinois Department of Revenue
The state agency responsible for administering and collecting Illinois taxes.
David Harris
The director of the Illinois Department of Revenue.
U.S. Postal Service
The federal agency responsible for mail delivery in the United States, which has updated its postmark procedures.
What they’re saying
“'If you're mailing your return close to the deadline, consider requesting a manual postmark or allowing extra time for delivery.'”
— David Harris, IDOR Director
“'Filing electronically is still the easiest way to make sure your return or payment is submitted on time.'”
— David Harris, IDOR Director
What’s next
Taxpayers can review the USPS guidance published in the Federal Register for more information on the postal service changes.
The takeaway
The new USPS postmark policy could create challenges for Illinois taxpayers mailing returns close to the April 15 deadline, underscoring the importance of filing electronically or allowing ample time for physical mail delivery to avoid potential penalties or delays.
