Research and development tax relief can provide valuable support to UK businesses. It allows companies to recover costs linked to innovation, improve cash flow, and reinvest in growth. However, the rules are detailed, and HMRC now reviews claims more closely than before.

In recent years, HMRC has increased compliance checks due to a rise in incorrect and inflated claims. Many enquiries are not triggered by fraud but by simple mistakes, unclear explanations, or weak supporting evidence.

This guide explains the most common mistakes that lead to HMRC enquiries and how your business can avoid them. Businesses that rely on research and development tax relief services should take extra care to make sure claims are accurate and well supported.

Why HMRC Is Scrutinising R&D Claims

R&D tax relief is a generous scheme. It is also complex. HMRC has identified a high level of error in claims submitted by businesses, especially those relying on third parties with limited technical understanding.

To protect the system, HMRC now carries out more checks before and after claims are submitted. This includes reviewing technical justifications, cost breakdowns, and company eligibility.

Many businesses now take a more structured approach to claims. Apex Accountants & Tax Advisors Ltd. supports businesses by focusing on clear documentation, accurate cost allocation, and compliance with HMRC requirements.

If your claim raises questions, HMRC may open an enquiry. This can delay your tax relief and require detailed explanations.

Key Errors That Often Lead to HMRC R&D Claim Reviews

Many R&D tax relief enquiries arise from avoidable errors rather than deliberate misreporting. HMRC expects claims to be clear, accurate, and supported by evidence. By understanding these common issues, businesses can prepare stronger claims and reduce the risk of delays or enquiries.

1. Claiming Activities That Do Not Qualify as R&D

One of the most common mistakes is claiming work that does not meet HMRC’s definition of R&D.

For a project to qualify, it must aim to achieve an advance in science or technology. It must also involve technical uncertainty that competent professionals cannot easily resolve.

Businesses often claim for activities such as:

• Routine software updates

• Minor product improvements

• Market research or design work

• Standard engineering tasks

While these activities may be valuable, they do not qualify for R&D tax relief.

How to avoid this mistake: Clearly identify where genuine technical challenges exist. Focus on projects that push knowledge or capability, not routine work.

2. Weak or Generic Technical Narratives

HMRC expects a clear explanation of the R&D work carried out. Many claims fail because the technical narrative is too vague or generic.

Common issues include:

• Using broad statements without technical detail

• Copying generic descriptions across multiple claims

• Failing to explain the uncertainty or the solution

A weak narrative makes it difficult for HMRC to understand why the work qualifies.

How to avoid this mistake: Provide a detailed, project-specific explanation. Describe:

• The scientific or technological goal

• The uncertainty faced

• The work carried out to resolve it

• The outcome

Use simple but precise language.

3. Incorrect Cost Calculations

Errors in cost calculations are a major trigger for enquiries. Businesses often include costs that are not eligible or fail to apply the correct rules.

Common mistakes include:

• Including non-R&D staff costs

• Claiming 100 percent of staff time without evidence

• Incorrect treatment of subcontractor costs

• Including capital expenditure

HMRC expects a reasonable and evidence-based approach to cost allocation.

How to avoid this mistake: Only include qualifying costs such as:

• Staff salaries linked to R&D

• Employer National Insurance and pension contributions

• Consumables used in the project

• Software costs related to R&D

Keep clear records to support how costs are calculated.

4. Lack of Supporting Evidence

Many businesses prepare claims after the project has finished, without keeping proper records during the work. This creates gaps in evidence.

HMRC may ask for:

• Project documentation

• Timesheets or staff allocation records

• Technical reports

• Financial records

If you cannot support your claim, it is more likely to be challenged.

How to avoid this mistake: Keep records throughout the project. Even simple documentation can help, such as:

• Project plans

• Meeting notes

• Development logs

• Internal reports

Good record keeping strengthens your claim.

5. Claiming for Subcontracted Work Incorrectly

The rules for subcontracted R&D are complex. Mistakes in this area often trigger enquiries.

For example:

• SMEs can claim for subcontracted work under certain conditions

• Large companies using the RDEC scheme have different rules

• Payments to connected parties must be treated carefully

Incorrect treatment can lead to overclaimed relief.

How to avoid this mistake: Review the contract and understand who is carrying out the R&D and who bears the risk. Apply the correct rules based on your scheme.

6. Overclaiming or Inflating the Value of Work

Some businesses overestimate the proportion of work that qualifies as R&D. This may be due to optimism or poor understanding of the rules.

Overclaiming can include:

• Applying high percentages of staff time without evidence

• Including entire projects when only part qualifies

• Inflating costs to increase the claim

This is a key risk area for HMRC.

How to avoid this mistake: Take a balanced and realistic approach. Only claim for work that clearly meets the criteria. Support your estimates with evidence.

7. Submitting Claims Without the Required Information

HMRC now requires additional information for R&D claims. Missing or incorrect details can lead to delays or enquiries.

This includes:

• The Additional Information Form

• Details of projects and costs

• Information about agents involved in the claim

Incomplete submissions are more likely to be reviewed.

How to avoid this mistake: Check that all required information is submitted accurately and on time. Review your claim carefully before submission.

8. Hiring Unqualified Advisors

Some businesses rely on advisors who focus on maximising claims rather than ensuring compliance. This can increase the risk of errors.

Poor advice may result in:

• Claims that do not meet HMRC criteria

• Weak technical explanations

• Incorrect cost calculations

HMRC may still hold the business responsible for the claim.

Working with experienced advisors offering comprehensive research and development tax relief services in the UK can help reduce risk and improve claim quality.

How to avoid this mistake: Work with advisors who understand both tax rules and the technical aspects of R&D. A compliant claim is more valuable than an inflated one.

9. Claiming Without Understanding Eligibility

Some businesses submit claims without fully understanding whether they qualify. This often leads to rejected claims or enquiries.

For example, companies may:

• Claim for commercial or aesthetic work

• Misinterpret what counts as innovation

• Assume all development work qualifies

How to avoid this mistake: Review HMRC guidance and assess eligibility before preparing your claim. If in doubt, seek professional advice.

10. Failing to Review Claims Before Submission

Rushing a claim increases the risk of mistakes. Errors in figures, descriptions, or eligibility can all trigger HMRC questions.

How to avoid this mistake: Carry out a thorough review before submission. Check:

• Technical explanations

• Cost calculations

• Supporting evidence

• Compliance with HMRC requirements

A careful review reduces risk.

What Happens If HMRC Opens an Enquiry

If HMRC raises questions about your claim, they may open an enquiry. This does not mean your claim is incorrect, but it does require a response.

You may need to:

• Provide additional documents

• Explain your technical work

• Justify your cost calculations

Enquiries can delay payments and require time and resources to resolve.

How to Reduce the Risk of HMRC Enquiries

To reduce the risk of an enquiry:

• Focus on genuine R&D projects

• Provide clear and specific technical explanations

• Keep accurate records

• Apply correct cost calculations

• Submit complete and accurate information

• Take a balanced approach to claims

A well-prepared claim is less likely to be challenged.

Final Thoughts

R&D tax relief can support innovation and provide valuable financial benefits. However, the process requires careful attention to detail.

Most HMRC enquiries are triggered by avoidable mistakes such as unclear narratives, incorrect costs, or lack of evidence. By understanding these risks and taking a structured approach, businesses can submit stronger and more compliant claims.

If your business is planning to claim R&D tax relief, taking the time to prepare properly can make a significant difference. A clear, accurate, and well-supported claim not only reduces risk but also improves the chances of a successful outcome.

Need Support with Your R&D Claim?

R&D tax rules can be complex. Getting it right the first time can save time, reduce risk, and protect your business.

Apex Accountants provides tailored research and development tax relief services in the UK, helping businesses prepare accurate and compliant claims.

Our team focuses on clear documentation, practical advice, and full compliance with HMRC requirements. A structured and well-prepared claim not only reduces the risk of enquiries but also helps you secure the full benefit of the relief available.