The Illinois Department of Revenue (IDOR) recently extended the deadline for business taxes filed for the state of Illinois. The reasoning is that the new tax law has many businesses confused and struggling with its complexity. Since the state due date coincided with the federal due date, IDOR chose to extend the state deadline one more month, to allow these businesses to file their federal returns first, and then follow up with their state return.

The Department will approve requests for abatement of penalties for late filing of any Forms IL-1120, IL-1120-ST, IL-1065 and IL-1041 due to reasonable cause on a case-by-case basis, provided those returns are filed on or before November 15, 2018. Please note: Requests for abatement should be made after a notice has been sent and received by the taxpayer.

More here, including contact information for filing abatements: Illinois Business Income Tax Deadlines Extended – Press Releases & News Archive