2024 Illinois State Tax Deadlines

Illinois Individual Income Tax Filing deadlines and extensions for 2024

If you are a resident or have been involved in significant business operations within Illinois, then you might be required to file Illinois State Taxes. We examine the most crucial tax deadlines and tax extensions for Illinois in 2024.

Illinois Business Tax Deadlines for 2024

C Corporation

Illinois C Corporation Tax Deadlines for 2024

You must file & pay Corporate Income Taxes in Illinois by April 15, 2025.

File by Mail must be postmarked by the due date.

Form

Form IL-1120 –Corporation Income and Replacement Tax Return.

Extension to File Taxes in Illinois for 2024

You must send payment for taxes in Illinois for the tax year 2024 by April 15, 2025.

The Extension Deadline is November 15, 2025, to file your Illinois corporate income tax return.

This is an extension to FILE, not an extension to PAY – payment is still due April 15, 2025.

Pass-Throughs

Illinois S Corporation & Partnership Tax Deadlines for 2024

You must file in Illinois by April 15, 2025.

File by Mail must be postmarked by the due date.

Forms

Form IL-11065 – Partnership Replacement Tax Return

Form il-1120 S – ST  Small Business Corporation Replacement Tax Return

Extension to File S Corporation & Partnership Taxes in Illinois for 2024

Partnership - You must send a payment for taxes in Illinois for the tax year 2024 by April 15, 2025.

The Extension Deadline is October 15, 2025, to file your Illinois partnership tax return.

S Corporation - You must send a payment for taxes in Louisiana for the tax year 2024 by March 15, 2025.

The Extension Deadline is October 15, 2025, to file your Illinois small business corporate tax return.

Illinois automatically grants a 6-month extension for filing partnership tax returns and a 7-month extension for small business corporate tax returns.  This means you do not need to file for an extension in Illinois.

This is an extension to FILE, not an extension to PAY – payment is still due March 15, 2025.

Illinois Individual Tax Deadlines for 2024

Estimated Tax Deadline for Illinois 2024:

  • Estimated tax payments can be made in four equal installments based on either 90% of the expected liability for the year 2024 or 100% of the liability for the year 2023 to avoid penalties, provided payments are made timely.

Individual Tax Deadline for Illinois 2024:

  • You must file and pay Individual Income Taxes in Illinois by April 15, 2024. Extensions are available that extend the filing deadline to October 15, 2024. However, this extension is to file, not an extension to pay—any owed taxes are still due by April 15, 2024​​​​.

Extension to File Taxes in Illinois for 2024:

  • Illinois automatically grants a 6-month extension for filing individual income taxes, making the extended deadline October 15, 2024. No specific action is required to obtain this extension, but it's essential to note that it does not extend the time to pay any taxes due​​.

Estates, Trusts, and Other Tax Deadlines

  • For estates and trusts, Illinois has specific filing requirements and deadlines that may differ. It's recommended to consult the Illinois Department of Revenue for the most current information and guidelines​​.

Farmer and Fisherman Taxes for Illinois 2024

  • Farmers and fishermen with at least two-thirds of their gross income derived from farming or fishing have specific guidelines for estimated tax payments and filing deadlines. Detailed advice should be sought from a tax professional or the Illinois Department of Revenue to ensure compliance with these specialized rules​​.

Sources

The material discussed on this page is meant for general illustration and/or informational purposes only and is not to be construed as investment, tax, or legal advice. You must exercise your own independent professional judgment, recognizing that advice should not be based on unreasonable factual or legal assumptions or unreasonably rely upon representations of the client or others. Further, any advice you provide in connection with tax return preparation must comply in full with the requirements of IRS Circular 230.

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