USPS Postmark Changes Could Affect 2026 Tax Filings
The Illinois Department of Revenue (IDOR) is notifying taxpayers that recent United States Postal Service (USPS) postmark changes may affect timely filing for 2026 returns and payments.
What’s Changing
- USPS automated postmarks may no longer reflect the dates taxpayers drop off mail at their local post offices.
- This may affect time‑sensitive documents, including tax returns and payments.
- Manual postmarks remain available free of charge at USPS retail counters upon request.
IDOR’s Recommendations
- Mail early—don’t wait until April 15.
- If mailing close to the deadline, request a manual postmark at the post office counter.
- Whenever possible, file and pay electronically for the fastest and most reliable processing.
Electronic Filing Benefits
- Ensures returns and payments are received on time.
- Free tax preparation is available for qualified individuals.
- Taxpayers may also use MyTax Illinois to file and pay electronically at no cost.
In‑Person Options
- Taxpayers who are not required to file electronically may drop off returns or payments at any IDOR office.
- IDOR staff will date stamp documents, providing proof of receipt.
Plan Ahead
- Review due dates at tax.illinois.gov
- Allow extra mailing time if sending returns or payments by mail
- Request a manual USPS postmark if mailing near the deadline
- Consider dropping off documents at an IDOR office for an official date stamp
- Use electronic filing to avoid mailing delays entirely