While some deadlines are for the 2023 tax year, the table below also includes deadlines for upcoming tax years and those set by the IRS or federal government.
April 15, 2025
Tax Year 2024
Income Tax Return
Prepare and e-File an IRS (Due Date April 15, 2025) and Illinois State Income Tax Return (Due Date April 15, 2025) until October 15, 2025. -
eFileIT
April 15, 2025
2024 Income Tax Extension
Tax Year 2024
Income Tax Return after the April 15, 2025 Illinois Tax Extension
Last day to e-File a 2024 Illinois State Income Tax Return for Tax Extension Filers and late eFilers. You can
only e-File (to file by paper see below) Illinois Income Tax Return together with an IRS Tax Return.
eFileIT
October 15, 2025 via mail-in Forms.
Forms incl. Mailing Address are listed below.
Tax Year 2024
Income Tax Return after the April 15, 2025 Illinois Tax Extension
Deadline for taxpayers who got a IL Tax Extension to file their Illinois Income Tax Return by mail-in Forms - the Forms incl. mailing addresses are listed below - is October 15, 2025. (Optionally, the
eFileIT deadline is Oct. 15, 2025). Instructions on how to
only - without the IRS return -
prepare and file an Illinois State Income Tax Return on eFile.com.
Tax Amendment for all Tax Years
IRS Due Dates
IRS Tax Return, Extension, Amendment Deadlines
2025, 2026, etc.
Other State Tax Return, Extension, Amendment Deadlines
2025, 2026, etc.
IRS Federal Income Tax Return, Amendment, Extension Deadlines
April 15, 2028
2024 Illinois Income Tax Return Refund.
IRS Tax Return Refund Claim DeadlineThe last day to file - you will not face late filing penalties - and claim your 2024 Illinois Income Tax Return Refund. This deadline does not apply if you owe 2024 Income Taxes.