R&D tax credit calculator

How is this figure calculated?

Your estimate is based on the merged R&D scheme, which has applied to most companies for accounting periods beginning on or after 1 April 2024. Under this scheme, qualifying expenditure earns a taxable expenditure credit, similar in structure to the old RDEC, and worth around 20% of qualifying costs before tax.

Loss-making SMEs with high research intensity may instead qualify for Enhanced R&D Intensive Support (ERIS), a separate scheme offering a more generous rate. To qualify, your R&D expenditure must be at least 30% of your total expenditure, including that of any connected companies.

Read more about how the merged scheme works, and how it differs from the two regimes it replaced, on our R&D tax relief service page.

What’s changed?

The R&D regime continues to tighten, though the direction of travel is more reassuring than it once looked. HMRC’s Annual Report and Accounts 2025-26 shows the estimated error and fraud rate has fallen to 5.3%, made up of 11.1% for the SME scheme and 3.2% for RDEC, down from 7.8% two years earlier, while total R&D relief support rose to £8 billion. As our tax team notes in our full breakdown of HMRC’s latest figures, the regime remains a valuable incentive, but HMRC continues to strengthen compliance activity, making it more important than ever for claims to be robust and well evidenced.

Two further changes are worth knowing about:

• Mandatory agent registration: From 18 May 2026, tax agents can register with HMRC voluntarily, becoming mandatory from 18 August 2026 for anyone providing R&D tax advice or submitting claims on a client’s behalf. If you use an adviser, it’s worth checking they’re registered.
• HMRC’s Advance Assurance pilot,: Launched in spring 2026, lets some companies get a formal HMRC opinion on a claim’s eligibility before submitting it, a way to de-risk a claim ahead of time rather than finding out after filing.

Getting your claim right

It remains the company’s responsibility to self-assess its eligibility for an R&D claim. Ensuring accuracy is crucial, as HMRC can impose financial penalties for errors. When deciding whether to impose a penalty, and how much, HMRC considers whether the company took reasonable care, including the effort put into the claim and the involvement of any external R&D specialists. A thorough review before submission is the best way to reduce that risk.

If you believe you’re entitled to an R&D tax refund, it’s worth seeking advice as early as possible. The claim and calculation process is complex, so talk to our R&D tax relief team about the steps you need to take.

Disclaimer

Our calculator tool is designed to provide a useful estimate of potential claim value only. It does not constitute nor replace the need to seek professional advice.

Your exact return will depend on a large number of factors specific to your particular business and your particular scenario, in addition to needing to undergo a thorough review of qualifying expenditure, proportionality and other factors such as the use of subcontractors in R&D activities.

If you want to understand further what these changes might mean for you, or you are claiming for the first time and would like our support in calculating and filing your claim, then please get in contact with our team using the form below.