Around one in six, on HMRC’s latest figures: it checked 17% of R&D claims in 2023-24, the most recent year it has published, up from 10% the year before. That was 9,700 compliance checks against roughly 61,000 claims received that year, by a compliance team it put at more than 500 staff. Any figure an adviser quotes about enquiry likelihood should be read against that base rate: this is now a relief where scrutiny is normal, not exceptional, and the sensible planning assumption is that your claim will be read critically.
What the numbers say
The scrutiny is working, which is why it will not be relaxed. HMRC’s July 2026 annual report shows estimated error and fraud in the relief falling from 17.6% in 2021-22 to 6.4% in 2023-24 on random-enquiry evidence, with illustrative estimates of 5.3% for the two years since. Claim volumes meanwhile fell 17% to 40,325 in 2024-25. That count comes from the statistics publication, which is built on a different basis from HMRC’s compliance figures. The publication’s revised count for 2023-24 is 48,610 claims, against the 61,000 claims received that year in the compliance figures, so dividing 9,700 checks into 48,610 does not give you the check rate. Fewer, larger, better-prepared claims, checked more often: that is the current shape of the regime, and it is the environment every claim now enters. We read the statistics in full in our guide to HMRC’s R&D tax credit statistics.
Payment is not the finish line either. HMRC runs what amounts to a process-now, check-later system: most claims are paid without a compliance check, and an enquiry can arrive after the money has been received and spent. If the claim proves wrong, relief is repaid, potentially with interest and penalties. A paid claim is a processed claim, not an approved one.
What an enquiry is, and what decides it
An enquiry is not a verdict; it is a demand to evidence the claim. HMRC will typically ask for technical explanations of each project, evidence of the scientific or technological uncertainties, the cost workings, staff roles and time allocation, subcontractor agreements and contemporaneous records. The standard of the original preparation usually decides the outcome: claims built on real technical input and reconciled costs close enquiries; claims reconstructed after the event, or written by someone who never spoke to the engineers, are the ones that unravel.
That is also why the honest answer to “how do I avoid an enquiry” is partly outside anyone’s control. Selection is HMRC’s, and it is not even-handed: its approach document says the extra checks went especially to claims made by SMEs, reflecting the higher error and fraud rates in that population. A well-prepared Additional Information Form reduces the invitation without eliminating the risk. What is fully in your control is whether an enquiry, if it comes, finds a claim that stands up.
Where to go next
Our HMRC enquiries guide explains the process stage by stage and how to respond; enquiry support is included as standard for claims we prepare. If you are facing an enquiry on a claim someone else filed, we take those on as a separate engagement, and we will tell you the truth about the claim’s strength first. R&D tax enquiry defence sets out how that work runs.
Sources
- HMRC’s approach to R&D tax reliefs 2023 to 2024 — 9,700 compliance checks against 61,000 claims received in 2023-24, the 500-staff figure, and the weighting of checks towards SME claims.
- HMRC annual report and accounts 2025 to 2026 (HC 350) — the error and fraud estimates at page 107 and Figure 20 of the report: 6.4% measured for 2023-24, and 5.3% illustrative for 2024-25 and 2025-26.
- Research and Development Tax Credits Statistics: September 2026 — claim volumes for 2024-25, and HMRC’s revised claim count of 48,610 for 2023-24.
This page describes the rules as they stood at the review date above, as general information rather than advice on your circumstances. For how that distinction works, see our terms; for an answer on your own facts, talk to us.