Far likelier than it used to be. HMRC checked around one in six R&D claims (17%) in 2023-24, the most recent year it has published, up from 10% the year before, with 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 a measured 6.4% in 2023-24, with illustrative estimates of 5.3% for the two years since — while claim volumes fell 26% to 46,950 in 2023-24. 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 key insights from HMRC’s 2025 R&D 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 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 we defend claims; 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 too, and we will tell you the truth about its strength first.
Written by Matthew Jones ACA CTA. Last reviewed July 2026.
Sources
- HMRC’s approach to R&D tax reliefs 2023 to 2024 — the 17% compliance coverage and 500-staff figures.
- HMRC annual report and accounts 2025 to 2026 — the error and fraud estimates: 6.4% measured for 2023-24, 5.3% illustrative for the years since.
- R&D tax credits statistics, September 2025 — claim volumes and values.
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.