The Illinois Department of Revenue announced on Mar. 16 that recent changes by the United States Postal Service regarding postmarks could affect how taxpayers file their returns in 2026.
This update is important because the USPS postmark will now show the date of the first automated processing operation, which may not match the date a taxpayer drops off mail at a local post office. This change could impact time-sensitive documents such as tax returns and payments.
The department is urging taxpayers who mail their returns and payments to send them earlier than usual to meet the April 15 filing deadline. “Our goal is to help taxpayers avoid unnecessary stress and penalties,” said David Harris, Director of the Illinois Department of Revenue. “If returns are mailed, taxpayers should not wait until the last day, or they should request manual postmarks at the post office if they are mailing a return near the filing deadline.” The USPS will continue to provide manual local postmarks upon request at retail locations free of charge, ensuring that these reflect when USPS first takes possession of mail.
Harris also said that electronic filing remains the most reliable way for timely submission: “The most reliable method to ensure IDOR receives a return or payment on time is to submit them electronically. Taxpayers may visit tax.illinois.gov for free electronic tax filing and payment options and use MyTax Illinois to file a return and make payments for free.” For those not required by law to file or pay electronically, documents can be dropped off at an IDOR office where staff will date stamp them as proof of receipt.
“Planning ahead is the best way taxpayers can protect themselves from late penalties,” Harris said. “Allowing extra mailing time, obtaining a manual postmark or IDOR date stamp, or using electronic filing options can reduce delays and ensure returns and payments are received on time.”
The Illinois Department of Revenue works to foster an inclusive environment that values diversity and equity for employees and customers, as stated on its official site. The agency focuses on fairly administering state tax laws and efficiently collecting revenues while providing accurate information according to its official website. It serves as a state agency dedicated to promoting diversity in its operations according to its official site, oversees collection of state taxes, delivers reliable financial information according to its official website, and operates within state taxation and revenue management as detailed on its official website.
For more details about these postal changes, taxpayers are encouraged to review guidance published in the Federal Register (90 Fed. Reg. 52883) and consult instructions available in the Tax Forms Index.
