You can spend thousands developing new software, products, or processes and still have your R&D tax credit claim rejected by HMRC. The problem is often not the innovation itself. It is how the project, costs, evidence, and filing requirements were handled.
HMRC now expects businesses to prove exactly what technological advance they sought and why the solution was not readily available. Weak technical explanations, unsupported costs, and missed deadlines can quickly put a claim at risk.
For directors, that can mean delayed repayments, reduced relief, lengthy enquiries, or penalties. This guide explains the main reasons HMRC challenges R&D claims and how to make yours more defensible from the start.
Key Takeaways
- Innovation alone does not make a project eligible for R&D relief.
- HMRC expects evidence of a scientific or technological advance.
- Incorrect or unsupported expenditure can cause HMRC to reduce the claim or disallow particular costs.
- Missing mandatory forms can make an otherwise eligible claim invalid.
Why R&D Claims Fail
An R&D tax credit claim can fail for two very different reasons. HMRC may treat a claim as invalid because the company failed to meet a filing requirement. Alternatively, HMRC can open an enquiry and later disallow some or all of the claim. This distinction matters. A strong technical project cannot overcome a missed statutory filing requirement.
The Project Does Not Qualify
The first question is whether the project meets HMRC’s definition of R&D.
For tax purposes, a project must seek an advance in science or technology. The advance must relate to the wider field rather than only improving the company’s own knowledge. Creating a new product does not automatically qualify.
For example, a company might develop a new customer portal using established software methods. The project could be commercially innovative without advancing software technology.
HMRC specifically states that simply using science or technology does not make an activity qualifying R&D.
A strong claim should therefore explain:
• What scientific or technological field applies.
• What knowledge existed before the project?
• What advance the company sought.
• Why that advance represented more than routine development.
Technological Uncertainty Is Poorly Explained
A qualifying R&D project must address scientific or technological uncertainty. This means a competent professional could not readily determine whether an advance was possible or how to achieve it.
Commercial difficulty does not qualify. Uncertainty about customer demand, project costs, or profitability is different from technological uncertainty.
HMRC expects businesses to explain the exact technical problem, the advance being sought, and why existing knowledge could not readily solve it. Generic statements such as “the project was innovative” or “technically challenging” are not enough.
A strong explanation should cover:
• the existing technological baseline
• the advance being sought;
• the specific uncertainty;
• why a competent professional could not readily solve it;
• testing, development, or failed approaches.
For example, a manufacturer should explain the technical limitation it needed to overcome, rather than simply stating that it developed a more efficient machine.
Costs Are Claimed Incorrectly
A qualifying project does not make every business expense eligible.
Eligible costs can include staffing, software, consumables, data licences, cloud computing, externally provided workers, and qualifying contractor costs. Costs such as rent, rates, land, patents, trademarks, capital expenditure, production, and distribution generally do not qualify.
A common mistake is applying one estimated percentage across the entire profit and loss account. For example, a technical director earning £80,000 should not automatically have their full salary included. The company should claim only the proportion linked to qualifying R&D activity.
Contractor Rules Are Misapplied
Contractor expenditure needs particular care under the reformed R&D rules. For accounting periods beginning on or after 1 April 2024, a company can generally claim contracted R&D where it decided the R&D was required and planned the activity.
For an unconnected contractor, 65% of the qualifying payment can normally be included. Different rules apply to connected contractors. Overseas contracted R&D is generally restricted, although limited exceptions apply.
(Source: HMRC: Check what R&D costs you can claim)
Additional Information Is Missing
Companies making an R&D claim must submit an Additional Information Form before, or on the same day as, the relevant corporation tax return. Where both are submitted on the same day, the Additional Information Form must be filed first.
The form includes details about the company, qualifying expenditure, R&D projects, internal contacts, and advisers. Failure to meet this requirement can make the R&D claim invalid.
This is why R&D work should be coordinated with proper corporation tax return preparation.
Claim Notification Was Missed
Some companies must notify HMRC before making an R&D claim. This generally includes first-time claimants and companies whose previous R&D claim falls outside HMRC’s three-year test. Where notification is required, the deadline is normally six months after the end of the period of account.
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Key R&D Deadlines
|
Requirement |
General deadline |
|
Claim notification |
Six months after the period of account ends |
|
Additional Information Form |
Before, or on the same day as, the CT600 |
|
Main R&D claim |
24 months from the period end where the period of account is 18 months or less |
|
Appeal against many HMRC decisions |
Usually within 30 days |
Different rules apply where the period of account exceeds 18 months. In those cases, the deadline is generally 42 months from the first day of the period of account.
(Source: HMRC: Make a claim for R&D tax relief on your Company Tax Return )
The Wrong Scheme Is Used
HMRC confirms that the merged R&D expenditure credit scheme and ERIS apply to accounting periods beginning on or after 1 April 2024.
Eligible companies can claim under the merged scheme, while qualifying loss-making R&D-intensive SMEs may claim ERIS instead. The R&D intensity threshold is generally 30%, subject to the detailed rules and relevant connected-company expenditure.
Using the wrong scheme can create an incorrect corporation tax position and increase HMRC risk.
(Source: HMRC/GOV.UK: Enhanced support for R&D-intensive SMEs)
Financial Records Do Not Match
An R&D claim should agree with the company’s wider financial records. HMRC may compare the figures against payroll, bookkeeping records, statutory accounts, tax computations, invoices, and contracts.
For example, an R&D schedule may show £200,000 of qualifying staff costs while payroll records support only £135,000. That difference needs a clear explanation.
Strong statutory accounts preparation should help reconcile the R&D calculation with the financial statements.
Directors Rely Completely on Advisers
Professional support can improve an R&D claim, but directors should still understand what is being submitted.
They should check whether the technical explanation matches the actual work and whether the costs agree with company records.
Businesses should also be cautious where an adviser focuses mainly on the size of the potential refund. A good adviser should test eligibility before calculating the benefit.
Can HMRC Charge Penalties?
A rejected R&D claim does not automatically result in a penalty. Penalties can arise where an inaccurate corporation tax return results from careless or deliberate behaviour.
|
Behaviour |
Unprompted disclosure |
Prompted disclosure |
|
Careless |
0% to 30% |
15% to 30% |
|
Deliberate, not concealed |
20% to 70% |
35% to 70% |
|
Deliberate and concealed |
30% to 100% |
50% to 100% |
These percentages apply to the potential lost revenue caused by the inaccuracy, rather than automatically applying to the total value of the R&D claim.
Reasonable care remains important. Directors should keep supporting records, review advisers, and understand significant tax claims before submission.
(Source: Corporation Tax: penalties – GOV.UK)
How to Reduce HMRC Risk
Before submitting an R&D tax credit claim, review the project from HMRC’s perspective. Ask whether a competent professional can clearly explain the technological advance. Then check whether the claimed expenditure follows the current rules.
A useful pre-submission checklist includes:
• Confirm the relevant field of science or technology.
• Document the technological uncertainty.
• Identify the competent professional.
• Separate routine development from qualifying activities.
• Reconcile expenditure to the accounting records.
• Review contractor arrangements carefully.
• Check whether claim notification is required.
• Submit the Additional Information Form before the CT600.
Strong documentation cannot turn an ineligible project into qualifying R&D. It can, however, make a valid claim much easier to support.
What Happens During an HMRC Enquiry?
An HMRC enquiry does not automatically mean the company has done something wrong. HMRC may request more technical or financial evidence before accepting the claim. A response should answer each question directly and connect the technical project with the claimed expenditure.
A strong response should show:
Project → technological uncertainty → qualifying activity → expenditure → supporting evidence
The explanation should remain consistent with the original claim unless there is a genuine reason for change.
Conclusion
An R&D tax credit claim needs more than evidence that a company developed something new. The project must meet HMRC’s scientific or technological tests, and the claimed expenditure must follow the current rules.
Businesses should also meet all filing requirements and keep clear technical and financial evidence. This can reduce the risk of delays, adjustments, or an HMRC enquiry.
If you are unsure whether your project qualifies, professional R&D tax support can help review the eligibility, qualifying costs, and corporation tax position before submission.
Get expert R&D tax advice to discuss your claim.
