Research and Development Expenditure Credit

The Research and Development Expenditure Credit, or RDEC, is a UK tax mechanism for supporting qualifying research and development. Its merged successor replaced the earlier RDEC and small-company routes for accounting periods starting on or after 1 April 2024. Most companies claiming research tax relief now use that merged scheme, including small firms outside the separate intensive-support route. [HMRC scheme history](https://www.GOV.UK/government/statistics/corporate-tax-research-and-development-tax-credit/research-and-development-tax-credits-statistics-september-2026)

Merged RDEC is a taxable credit for trading companies within corporation tax that undertake qualifying research. It treats the credit as trading income. Eligibility and qualifying expenditure determine the claim, with restrictions covering some overseas costs. A separate scheme, Enhanced R&D Intensive Support, serves eligible loss-making research-intensive small companies; the same spending cannot receive both forms of relief. [HMRC guidance](https://www.GOV.UK/guidance/research-and-development-rd-tax-relief-the-merged-scheme-and-enhanced-rd-intensive-support)