A Claim That Used to Take Weeks Now Takes Months
A finance director at a small UK software company submitted her firm's R&D tax credit claim in April, expecting the usual six-to-eight week wait before the payable credit landed in the company account. Three months later, she was still waiting — not because the claim had been rejected, but because it had been pulled into a compliance check and no caseworker had opened the file yet. Her experience is not unusual. Across the accountancy sector, advisers describe the same pattern repeating through 2026: claims that would once have cleared quietly are now sitting in a holding pattern while HMRC works through a growing volume of enquiries into Research and Development relief, one of the most heavily scrutinised corners of the UK tax system this year. For a cash-strapped small business that budgeted around the credit arriving on schedule, that delay is not an abstract inconvenience — it is a hole in the cash flow forecast that someone has to explain to the bank or the board.
If your company has claimed R&D relief at any point in the past three years, you have probably already noticed the process looks nothing like it did before 2022. Claims that once went through on a light-touch basis, with HMRC accepting the claimant's word on eligibility and cost apportionment, are now far more likely to be checked in detail before any money moves. That shift is deliberate, and it is not going away.
Why HMRC Tightened Its Grip on R&D Relief
The crackdown traces back to HMRC's own admission that error and fraud within the R&D schemes, particularly the old SME scheme, had reached a level the department considered unacceptable. A wave of claim-farm advisers spent several years encouraging companies to submit speculative or inflated claims on a no-win, no-fee basis, often for activity that would never have met the "seeking an advance in science or technology" test that sits at the heart of the relief. HMRC's response has been a sustained programme of reform rather than a single crackdown moment. Since 8 August 2023, every claim has needed a mandatory Additional Information Form submitted before the tax return, setting out the technical detail behind the work, the qualifying costs, and the identity of the agent involved. Companies claiming for the first time, or that have not claimed in the previous three years, must also notify HMRC within six months of the end of the relevant accounting period or lose the right to claim altogether — a rule that has already caught out businesses that assumed they had the usual two-year window to submit an amended return.
On top of the paperwork, the schemes themselves changed shape. Accounting periods beginning on or after 1 April 2024 fall under a merged R&D scheme that replaces the separate SME and RDEC regimes with a single RDEC-style credit, alongside a distinct Enhanced R&D Intensive Support (ERIS) rate for loss-making companies that spend a high enough proportion of their expenditure on qualifying R&D. Each of these changes gave HMRC a fresh reason to open a file and check that a claimant had applied the new rules correctly, rather than simply carrying over last year's approach.
What an Enquiry Actually Involves Now
HMRC no longer takes claimants' word for it.
A compliance check into an R&D claim typically starts with a formal letter asking for the technical narrative behind the Additional Information Form to be expanded — often requesting a "competent professional" statement from the person who actually did the work, not the finance team who wrote up the claim afterwards. From there, HMRC's specialist R&D caseworkers commonly ask for time-tracking records showing how staff hours were apportioned between qualifying and non-qualifying activity, subcontractor and externally provided worker invoices broken down by project, and evidence that the work involved genuine scientific or technological uncertainty rather than routine development using known methods. Where the claim involves subcontracted R&D or connected-party costs, expect a further round of questions about who directed the work and who bore the financial risk, since those details determine which company is entitled to claim under the merged scheme's rules.
Not Every Claim Gets This Treatment
It would be wrong to suggest every R&D claim now attracts a lengthy enquiry — most well-documented claims from established claimants with a clean compliance history still clear within a normal processing window. The claims most likely to be pulled for a full check share a few risk indicators: a claim value that looks large relative to the company's turnover or headcount, a first-time claimant with no track record, involvement of an adviser who has previously submitted claims HMRC later reduced or rejected, or a heavy reliance on subcontractors rather than in-house staff. Businesses that fall into none of those categories generally still see claims processed close to the standard timeline, even in the current environment.
The Practical Cost of Waiting
For a loss-making SME claiming under ERIS, the payable credit is often built into the cash flow plan for the following quarter, covering payroll, rent, or the next round of product development. A delay of three, four, or six months while an enquiry runs its course can force a business to draw on an overdraft, delay hiring, or renegotiate supplier terms — costs that rarely appear on HMRC's own timeline but land squarely on the claimant. And if the enquiry concludes that part of the claim was overstated, the company faces a reduced repayment plus interest on the excess, and in more serious cases a penalty for careless or deliberate inaccuracy. Getting the claim right the first time, rather than hoping HMRC waves it through, is the only strategy that actually protects the cash the business is counting on.
How to Reduce the Risk of a Lengthy Enquiry
Working with an adviser who belongs to a recognised professional body — ICAEW, ACCA, ATT or CIOT — is the safer choice; claim-only firms that charge a percentage of the refund and vanish once the money lands are not worth the risk, however attractive the upfront fee structure looks. Beyond choosing the right adviser, a handful of practical habits make the biggest difference to how smoothly a claim moves through HMRC's system:
- Keep contemporaneous records of the technical uncertainty being addressed and how it was resolved, written at the time the work happened rather than reconstructed months later for the claim.
- File the Additional Information Form with more technical detail than the bare minimum HMRC asks for — thin, generic narratives are the single most common reason enquiries get opened in the first place.
- Track staff time by project on an ongoing basis, since apportionment estimates produced retrospectively rarely survive close questioning.
- Meet the six-month notification deadline for new or lapsed claimants without exception, and diarise it separately from the tax return deadline itself.
- Respond to HMRC's first enquiry letter fully and promptly; slow or partial responses tend to invite a second and third round of questions, stretching a case that might have closed in weeks into one that runs for the better part of a year.
Advance assurance remains available for some very small first-time claimants, though eligibility is limited and it does not remove the need for solid contemporaneous evidence later. Treat it as one part of a broader approach, not a substitute for keeping the underlying records straight.
Living With the New Normal
The extra scrutiny is not a temporary phase that will ease once HMRC clears a backlog — it reflects a permanent shift in how the department treats R&D relief after years of high-profile abuse of the old rules. Businesses that treat their claim with the same rigour they would apply to an audited set of accounts, with records built as the work happens rather than assembled under enquiry pressure, are consistently the ones getting through the process fastest. Those still submitting claims the way they did in 2021, with a thin technical write-up and cost estimates pulled together at year end, are the ones most likely to be reading a compliance check letter next.