Illinois tax credits and incentives
Review the program rules and claim timing below, then confirm the requirements with the administering agency.
This directory is not tax advice. Confirm eligibility, tax-year rules, deadlines and filing requirements with a tax professional.
Amounts are subject to the conditions in each listing. A source review does not mean applications are open or that a business qualifies.
1 program
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Illinois research and development credit
Tax credit
6.5% of qualifying expenses above the base-period average. [Illinois 2025 Schedule 1299-D]
Check program requirements [Illinois 2025 Schedule 1299-I instructions][Illinois 2025 Schedule 1299-D]
Eligibility, claim steps and deadlines for Illinois research and development credit
- Who qualifies
- Taxpayers incurring qualifying research expenses for activities conducted in Illinois. [Illinois 2025 Schedule 1299-I instructions]
- What it’s worth
- 6.5% of qualifying expenses above the base-period average. [Illinois 2025 Schedule 1299-D]
- How to claim
- Use the research worksheet in Schedule 1299-I, then the applicable Schedule 1299-A, 1299-C or 1299-D; credit code 5340. [Illinois 2025 Schedule 1299-I instructions]
- Deadlines and application windows
- The opened instructions cover tax years ending before January 1, 2027. Confirm authorization before assuming eligibility for a later tax year. [Illinois 2025 Schedule 1299-I instructions]
Sources reviewed
Full details and sources for Illinois research and development credit