Illinois research and development credit
Tax credit
Agency: Illinois Department of Revenue. Agency source
This directory is not tax advice. Confirm eligibility, tax-year rules, deadlines and filing requirements with a tax professional.
Check program requirements [Illinois 2025 Schedule 1299-I instructions][Illinois 2025 Schedule 1299-D]
- 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]
Amounts are subject to the conditions in each listing. A source review does not mean applications are open or that a business qualifies.
Official sources
Listing reviewed