Illinois Nonprofit Tax Deadlines 2026
Complete guide to Nonprofit filing dates, extensions, estimated payment schedules, and required forms in Illinois for the 2026 tax year. Illinois imposes a state income tax, so Nonprofit entities must file both federal and state returns.
Illinois Nonprofit filing deadline
Nonprofit annual return generally due the 15th day of the 5th month.
Due: May 15, 2026
Extension: Nov 15, 2026
Form: State nonprofit return
Estimated payments
No state estimated payment schedule listed.
Due: N/A
Illinois Nonprofit Tax Calendar at a Glance
| Event | Date |
|---|---|
| Filing deadline | May 15, 2026 |
| Extension deadline | Nov 15, 2026 |
FAQ
When is the Nonprofit tax filing deadline in Illinois for 2026?
The Illinois Nonprofit tax return is due May 15, 2026 for the 2026 tax year. An extension is available until Nov 15, 2026.
Does Illinois require Nonprofit estimated tax payments?
Estimated payments are not typically required at the entity level for Nonprofit in Illinois, but confirm with Illinois Department of Revenue.
What form do I file for a Nonprofit in Illinois?
Nonprofit entities in Illinois file using Form State nonprofit return. You can download the form from Illinois Department of Revenue at https://tax.illinois.gov.
Can I get an extension for my Illinois Nonprofit tax return?
Yes. Illinois allows an extension for Nonprofit returns until Nov 15, 2026. Note that an extension gives you more time to file, not more time to pay — any tax owed is still due by the original deadline of May 15, 2026.
What are the penalties for filing late in Illinois?
Illinois typically charges a failure-to-file penalty (usually 5% of unpaid tax per month, up to 25%) and a failure-to-pay penalty (usually 0.5-1% per month). Interest also accrues on unpaid balances. Filing for an extension by the original deadline avoids the failure-to-file penalty but not the failure-to-pay penalty.
Where can I file Illinois Nonprofit taxes?
File through Illinois Department of Revenue. Visit https://tax.illinois.gov for e-filing options, downloadable forms, and payment portals.
Illinois Estimated Tax Payments
View the full quarterly estimated payment schedule for Illinois, including all entity types and payment methods.
View Illinois estimated payments →