R&D Tax Credits for UK SMEs: How to Claim What You Are Owed

What qualifies as R&D under HMRC's rules#

HMRC defines qualifying R&D as work that seeks to achieve an advance in science or technology by resolving a scientific or technological uncertainty — specifically, work where you do not know at the outset whether something is achievable or how to do it. This is broader than most founders realise. Building software that requires solving novel technical problems qualifies — even if the software is for internal use. Developing a new product formulation where the chemistry outcome is uncertain qualifies. Attempting to adapt existing technology to a new application where the technical feasibility is uncertain qualifies. Routine software development, cosmetic product changes, and social science research do not qualify.

The SME R&D relief scheme: how the numbers work#

For qualifying SMEs (fewer than 500 employees, turnover under €100 million or balance sheet under €86 million), the R&D relief works as follows. The company deducts 186% of qualifying R&D costs from taxable profits — meaning £100 of qualifying expenditure is treated as £186 of expense. For a company paying 25% corporation tax, this saves £21.50 per £100 of qualifying expenditure. For loss-making companies, HMRC offers a cash credit — the company can surrender the loss created by the R&D deduction in exchange for a cash payment of 10% of the surrendered loss. This means a loss-making company spending £100,000 on qualifying R&D could receive a cash payment from HMRC of approximately £10,000.

Qualifying cost categories#

The main qualifying cost categories for the SME R&D scheme: staff costs (salaries, employer NICs, and pension contributions of employees directly involved in qualifying R&D activities). Subcontractor costs (65% of payments to qualifying subcontractors conducting R&D on your behalf). Consumables (materials and software licences used and consumed in the R&D process). Externally provided workers (65% of payments to staffing agencies providing workers on qualifying R&D). Note: capital expenditure (equipment, computer hardware) does not qualify for R&D credits but may qualify for capital allowances.

How to claim R&D tax credits#

R&D tax credits are claimed through your annual corporation tax return (CT600) along with an R&D report that describes qualifying projects and provides the expenditure detail. The R&D report must include: a technical description of each project explaining the advance sought and the uncertainties involved, the qualifying expenditure by category, and a statement that the work meets HMRC's definition of R&D. Claims must be filed within 2 years of the end of the accounting period. Given HMRC's increasing scrutiny of R&D claims, the technical narrative quality has become critically important — vague or generic descriptions generate enquiries and delays.

Common R&D claim mistakes and HMRC scrutiny#

HMRC has significantly increased R&D claim enquiries since 2022, targeting poorly evidenced claims. Common mistakes: including routine development work that does not meet the uncertainty test, claiming 100% of staff time when only a portion was spent on qualifying R&D, using generic technical descriptions that could apply to any software company, and claiming subcontractor costs without verifying the subcontractor relationship meets HMRC's requirements. A well-evidenced claim with a specific technical narrative, contemporaneous time records, and clear cost documentation is the best protection against an enquiry. Many businesses use specialist R&D tax advisers on a contingent fee basis — justified by the complexity and the risk of a poorly structured claim.