Connecticut 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.
2 programs
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Connecticut corporate research and development credit
Tax credit
Tentative credit of 6% for qualified small businesses, subject to annual-use limits. Eligible businesses with gross income at most $70 million and no corporation tax liability may exchange credits at 65% or 90%, subject to eligibility restrictions. [Connecticut 2025 Form CT-1120 RDC instructions]
Check program requirements [Connecticut 2025 Form CT-1120 RDC instructions]
Eligibility, claim steps and deadlines for Connecticut corporate research and development credit
- Who qualifies
- Corporation Business Tax filers conducting qualifying Connecticut research. The small-business calculation requires prior-year gross income no greater than $100 million and satisfaction of related-party restrictions. [Connecticut 2025 Form CT-1120 RDC instructions]
- What it’s worth
- Tentative credit of 6% for qualified small businesses, subject to annual-use limits. Eligible businesses with gross income at most $70 million and no corporation tax liability may exchange credits at 65% or 90%, subject to eligibility restrictions. [Connecticut 2025 Form CT-1120 RDC instructions]
- How to claim
- Use CT-1120 RDC and CT-1120K. For an eligible exchange, file CT-1120 XCH separately with supporting schedules at the same time as the corporation return. [Connecticut 2025 Form CT-1120 RDC instructions]
- Deadlines and application windows
- Claim with the applicable tax-year forms. Current-year exchange limits apply; unused credits earned from 2021 may carry forward 15 income years. [Connecticut 2025 Form CT-1120 RDC instructions]
Sources reviewed
Full details and sources for Connecticut corporate research and development credit
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Connecticut partnership and S corporation research credit
Tax credit
6% of qualifying research expenses, up to $1.5 million per business and subject to the $25 million program cap. Eligible excess can be exchanged at 90% for biotechnology businesses or 65% for other qualifying businesses. [Connecticut Revenue 2026 enacted tax developments]
New program for tax years beginning in 2026 [Connecticut Revenue 2026 enacted tax developments]
Eligibility, claim steps and deadlines for Connecticut partnership and S corporation research credit
- Who qualifies
- Qualifying partnerships and S corporations with gross income no greater than $70 million, receiving DECD approval for eligible research expenditures. [Connecticut Revenue 2026 enacted tax developments]
- What it’s worth
- 6% of qualifying research expenses, up to $1.5 million per business and subject to the $25 million program cap. Eligible excess can be exchanged at 90% for biotechnology businesses or 65% for other qualifying businesses. [Connecticut Revenue 2026 enacted tax developments]
- How to claim
- Apply to DECD for a reservation, verify spending and obtain the credit voucher. Submit any refund-exchange claim with the tax return. The legislative overview does not identify a numbered form. [Connecticut Revenue 2026 enacted tax developments]
- Deadlines and application windows
- Applies to tax years beginning on or after January 1, 2026. Verify expenditures within 90 days after the tax year ends. [Connecticut Revenue 2026 enacted tax developments]
Sources reviewed
Full details and sources for Connecticut partnership and S corporation research credit