HMRC R&D Tax Relief Crackdown, What Small Businesses and Ltd Companies Need to Know
HMRC R&D Tax Relief Crackdown, What Small Businesses and Ltd Companies Need to Know
R&D tax relief has helped thousands of Ltd companies fund genuine innovation, but HMRC now believes a significant slice of past claims were wrong, exaggerated or outright fraudulent. The response has been a wave of new rules, tighter forms and far more compliance checks. All figures and rates in this guide are correct as of 18 September 2026.
Key takeaways
- Every claim now needs a mandatory additional information form, and many businesses must also submit advance claim notification before they claim.
- The old SME and RDEC schemes were replaced by a single merged R&D scheme for accounting periods starting on or after 1 April 2024.
- HMRC estimated error and fraud in R&D relief peaked at £1.13bn (16.7% of claims) for 2020–21, and enquiry numbers have risen sharply as HMRC works to bring that figure down.
- Careless or deliberately overstated claims can attract penalties of up to 100% of the tax relief obtained, on top of repaying the relief itself.
Why HMRC changed course on R&D relief
For years, R&D tax relief was seen as a relatively easy claim to make, and a cottage industry of aggressive "R&D boutiques" grew up encouraging businesses to claim for activity that was never genuinely eligible. HMRC's own Mandatory Random Enquiry Programme (MREP), which tests a representative sample of claims each year, exposed just how widespread the problem had become.
Important context
Not every business claiming R&D relief has done anything wrong. Most claims for genuinely innovative work remain valid and valuable. The crackdown targets claims for routine business activity dressed up as research, and cases where an adviser or director knowingly pushed a claim beyond what the rules allow.
The numbers behind the crackdown
HMRC's own statistics show why R&D relief has become such a compliance priority. The overall level of error and fraud has fallen steadily since its peak, but it remains one of the costliest problem areas in the tax system, and the SME element of the relief has consistently been the weakest link.
By HMRC's latest published estimates, the overall error and fraud rate had fallen to around 6.4% for 2023–24, with a further reduction projected for 2024–25 and 2025–26. That is real progress, but the SME scheme has continued to run at a noticeably higher error rate than the large-company RDEC element, which is exactly why HMRC's compliance teams remain focused on smaller claimants.
The merged scheme: one set of rules from April 2024
For accounting periods beginning on or after 1 April 2024, the separate SME and RDEC schemes were replaced by a single merged R&D expenditure credit scheme. Broadly, all companies now claim an "above the line" taxable credit, calculated at a standard rate, rather than choosing between the old SME super-deduction and the RDEC credit.
A separate, more generous Enhanced R&D Intensive Support (ERIS) regime remains available for loss-making SMEs that spend a high proportion of their total expenditure on qualifying R&D. The detailed rate calculations depend on your company's size, profitability and R&D intensity, so it is worth reviewing your position with your accountant under the current tax planning rules rather than assuming the old scheme still applies.
Warning
If your accounting period straddles 1 April 2024, or you are still working from guidance written for the old SME and RDEC schemes, do not assume the rates or rules are the same. Claims prepared on out-of-date assumptions are now one of the most common triggers for an HMRC compliance check.
Two new forms you cannot skip
Since 8 August 2023, every company making a new R&D claim has had to submit a mandatory Additional Information Form (AIF) to HMRC, before or on the same day as the Company Tax Return. Skip it, or file it in the wrong order, and HMRC will simply remove the R&D claim from your return, sometimes too late to correct.
On top of that, many companies must also submit a claim notification (sometimes referred to loosely as an advance notification) within six months of the end of the relevant period of account. This generally applies if you are claiming for the first time, or have not made an R&D claim in any of the previous three years.
What the forms must cover
- Company details, UTR, PAYE reference and VAT number, matching your Company Tax Return exactly.
- The name of the senior internal contact responsible for the claim, and details of any agent involved.
- A description of each qualifying project, including the baseline technology, the scientific or technological uncertainty, and how the project tried to resolve it.
- A breakdown of qualifying costs by category, split by project where more than one project is claimed.
What now triggers an HMRC enquiry
HMRC's compliance teams have significantly expanded the volume of R&D checks they open each year, and enquiry numbers have kept rising even as overall claim numbers have fallen. In practice, certain patterns catch HMRC's attention far more often than others.
Common red flags
- Claims for activity that reads as routine software development, product customisation or "business as usual" work rather than a genuine scientific or technological advance.
- Costs claimed for work that does not match the company's SIC code, trade or the technical narrative given.
- A claim prepared entirely by a third-party boutique with no named, contactable technical lead within the company.
- Inconsistent figures between the additional information form and the Company Tax Return, or missing PAYE, VAT and UTR details.
- A sudden first-time claim for a very large sum, with limited supporting technical or cost evidence.
The penalties if a claim is wrong
Where HMRC finds an error, the consequences depend on why it happened. A genuine mistake, corrected promptly and without carelessness, can sometimes attract no penalty at all beyond repaying the relief. Careless errors can bring penalties of up to 30% of the extra tax due, and deliberate, concealed errors can attract penalties of up to 100%, in addition to repaying every penny of relief claimed, plus interest.
Do not ignore an HMRC compliance check letter
If HMRC opens an enquiry into an R&D claim, respond within the stated deadline and take advice early. Failing to engage, or providing rushed or inconsistent answers, tends to make HMRC dig deeper rather than close the case.
Specialist adviser or general accountant?
R&D relief sits at the intersection of tax law and genuine technical assessment. A good general accountant can prepare your limited company accounts and corporation tax return to a high standard, but assessing whether a project meets the scientific or technological uncertainty test often benefits from someone who understands both the tax rules and your sector in detail.
The safest approach for many small businesses is a joint one: your accountant keeps the numbers, the accounting period and the Company Tax Return correct and consistent, while a genuinely qualified R&D specialist tests whether the underlying project work is eligible before anything is submitted. Be wary of any adviser who guarantees a claim size before reviewing your actual technical work, or who is paid purely on a percentage of the relief obtained with no interest in defending the claim later.
Keeping your claim compliant going forward
Practical next steps
- Check whether you need to submit a claim notification within six months of your period of account ending, before you do anything else.
- Confirm your claim is being prepared under the correct merged scheme or ERIS rules for accounting periods from 1 April 2024.
- Keep contemporaneous technical records for each project, written by the people who did the work, not reconstructed after the event.
- Make sure your additional information form and Company Tax Return match exactly on company details, dates and figures.
- Review any claim prepared by a third party before it is submitted, and keep evidence of who advised on it.
Well-organised, accurate limited company accounts and a clear tax planning strategy make it far easier to support a genuine R&D claim if HMRC ever asks questions.
How 360Accounts Can Help
Get your R&D position checked before you claim
Whether you are making your first R&D claim, reviewing an existing one under the merged scheme, or responding to an HMRC enquiry, we can help you understand what is genuinely eligible and what needs tightening up.
Speak to 360Accounts or view our pricing to get started.
Questions directors ask about the R&D crackdown
Does my business qualify for R&D tax relief?
You may qualify if your company is genuinely trying to achieve an advance in science or technology, and faced scientific or technological uncertainty that a competent professional in the field could not readily resolve. Routine customisation, applying existing techniques, or normal product development without a genuine technical uncertainty generally will not qualify. It is worth reviewing each project against this test individually, project by project, rather than assuming an entire department or product line automatically qualifies.
What does HMRC now require before I submit a claim?
Every claim needs a mandatory additional information form submitted before or alongside your Company Tax Return, covering company details, a named senior internal contact, and a technical description of each project. If you are claiming for the first time, or have not claimed in the previous three years, you will usually also need to submit a claim notification within six months of the end of your period of account. Missing either deadline can mean your claim is rejected outright.
What are the most common mistakes that trigger an enquiry?
The most frequent triggers are claims for routine or "business as usual" work described as research, inconsistencies between the additional information form and the Company Tax Return, claims prepared entirely by a third party with no accountable technical lead inside the business, and figures that do not match the company's PAYE, VAT or UTR records. A sudden, large first-time claim with thin technical evidence also tends to attract closer attention.
What happens if HMRC rejects or investigates my R&D claim?
HMRC will usually open a formal compliance check and ask detailed questions about the technical uncertainty, the work carried out and the costs claimed. If the claim cannot be supported, the relief is repaid with interest, and where HMRC considers the error careless or deliberate, a penalty of up to 30% or up to 100% of the extra tax due can also apply. Responding promptly, honestly and with proper technical evidence gives you the best chance of a fair outcome.
Should I use a specialist R&D adviser or my general accountant?
Both have a role. Your accountant should keep your accounting period, Company Tax Return and additional information form accurate and consistent, while a genuinely qualified R&D specialist can properly test whether your project work meets the scientific or technological uncertainty test. Be cautious of any adviser who promises a claim size before reviewing your actual technical work, or who has no interest in supporting the claim if HMRC later asks questions.
How do I make sure my claim is compliant going forward?
Check your claim notification deadline early, confirm you are applying the correct merged scheme or ERIS rules for accounting periods from 1 April 2024, keep contemporaneous technical notes written by the people who did the work, and make sure every figure matches across your forms and tax return. Reviewing any third-party prepared claim before submission, rather than after, is one of the simplest ways to avoid problems later.