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2023 Corporate Income Tax Forms

Name Description
IL-1120

Instructions

Corporation Income and Replacement Tax Return
IL-1120-V

Payment Voucher for Corporation Income and Replacement Tax

To make a return or extension payment, use this voucher and Appendix A of Form IL-1120 Instructions.
To make an estimated payment, use this voucher and Appendix B of Form IL-1120 Instructions.

Important: Ensure the proper month and year of the filing period you wish to make a payment for is entered on the "Tax year ending" lines of the voucher.

​IL-1120-X
Instructions
Amended Corporation Income and Replacement Tax Return
IL-1120-X-V

Payment Voucher for Amended Corporation Income and Replacement Tax

Important: Ensure the proper month and year of the filing period you wish to make a payment for is entered on the "Tax year ending" lines of the voucher.

IL-477 Instructions Replacement Tax Investment Credits
IL-2220 Instructions Computation of Penalties for Businesses
IL-4562

Instructions

Special Depreciation
Schedule INL Instructions Illinois Net Loss Adjustments for Cooperatives and REMIC Owners
Schedule INS Instructions Tax for Foreign Insurers
Schedule J Instructions Foreign Dividends
Schedule M Instructions Other Additions and Subtractions (for businesses)
Schedule NB Instructions Nonbusiness Income
Schedule NLD Instructions Illinois Net Loss Deduction
Schedule UB
02/23/24 - Updated Step 2, Line 25, to reflect
federal Form 1120, Line 25 (Energy efficient
commercial buildings deduction).
Instructions Combined Apportionment for Unitary Business Group
Schedule UB/INS Instructions Tax for a Unitary Business Group with Foreign Insurer Members
Schedule UB/NLD Instructions Unitary Illinois Net Loss Deduction
Schedule 80/20 Instructions Related-Party Expenses
Schedule 1299-B Instructions
River Edge Redevelopment Zone or Foreign Trade Zone (or sub-zone) Subtractions (for corporations and fiduciaries)
Schedule 1299-D

Instructions

07/10/24 – Updated to include new Quantum Computing Campuses tax credit.

Income Tax Credits (for corporations and fiduciaries)

Schedule 1299-I

07/10/24 – Updated to include new Quantum Computing Campuses tax credit and to extend expiration dates for credits affected by recently passed legislation.

Income Tax Credits Information and Worksheets
Schedule 4255

Instructions

Subgroup Schedule (UB) Instructions
Subgroup Schedule