Why Getting Expenditure Right Matters
Finance directors frequently focus on whether their company's technical activities pass HMRC's definition of R&D. That question matters, but it is only half the picture. An equally important question is: once qualifying activities are confirmed, which costs are actually claimable?
The value of an R&D tax credit claim is determined almost entirely by the qualifying expenditure figure. A company that correctly identifies its qualifying activities but underestimates its costs will receive a fraction of what it is legitimately owed. Equally, a claim that includes non-qualifying costs risks triggering an HMRC compliance check, which creates delay, expense, and potential penalties.
There are six categories of qualifying expenditure under the merged R&D Expenditure Credit scheme that has applied to all companies since April 2024: staff costs, subcontractor costs, externally provided workers, consumables, software licences, and data and cloud computing costs. Each category has specific rules. Understanding them properly, rather than relying on general assumptions, is what separates a well-prepared claim from one that leaves money on the table.
Common error: underestimating qualifying expenditure
In our experience reviewing initial client estimates, the most frequent mistake is omitting categories entirely rather than misidentifying activities. Companies routinely forget to include employer National Insurance contributions, miss externally provided worker costs, or fail to apportion pension contributions. A systematic cost review against each qualifying category consistently finds more than the client's initial estimate.
Staff Costs: The Foundation of Every Claim
For the majority of UK technology, engineering, and life sciences businesses, staff costs make up between 70% and 85% of total qualifying R&D expenditure. This is typically the most significant category and the one that demands the most careful calculation.
HMRC accepts three components of employee costs as qualifying R&D expenditure:
Gross salary. The employee's gross salary for the period they were engaged in qualifying R&D activities. This includes bonuses that relate directly to R&D performance. Holiday pay and sick pay taken during periods when the employee was otherwise engaged on R&D also count, provided the overall time apportionment is reasonable.
Employer National Insurance contributions. The employer's NIC on the qualifying portion of the employee's earnings is a claimable cost. This is employer NIC only, not the employee's own contributions.
Employer pension contributions. Contributions made by the employer into a registered pension scheme, apportioned to the qualifying time period, are included. Only employer contributions qualify; the employee's own pension deductions do not.
What is not included in staff costs: benefits in kind, expense reimbursements, and amounts above the statutory pension minimum where the excess cannot be attributed to R&D performance.
Worked calculation for a single qualifying engineer
Consider a senior software engineer with the following annual cost package:
The proportion of time spent on R&D is the critical variable in this calculation. HMRC expects it to be grounded in something reasonable and contemporaneous. Timesheets are the strongest form of evidence. Where timesheets do not exist, apportionments based on project records, sprint logs, meeting calendars, or a manager's documented assessment are accepted, but they must be internally consistent and applied in good faith.
Time apportionment: the five steps
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1
Identify qualifying employees
List every employee who directly performed or directly supervised qualifying R&D activities during the accounting period. Include directors, technical leads, and part-time staff if they engaged in qualifying work.
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2
Gather time evidence
Pull together timesheets, project management records, sprint data, version control logs, or any documented system that shows how each person's time was allocated across projects or work types.
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3
Map time to qualifying activities
For each qualifying R&D project, calculate the percentage of each employee's working time spent on activities that meet HMRC's technical uncertainty test. Exclude management, administration, and commercial activities from this percentage.
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4
Apply the percentage to the cost package
Multiply the gross salary, employer NIC, and employer pension contribution by the qualifying time percentage to arrive at the qualifying cost for each employee.
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5
Document and retain
Keep the underlying evidence and the apportionment calculation as part of the claim record. HMRC may request this during a compliance check, sometimes years after the claim is submitted.
Subcontractors and Externally Provided Workers
Many businesses engage subcontractors for specialist technical work or use staffing agencies to bring in additional resource. The R&D treatment depends on how the engagement is structured, not simply on whether the individual is on the payroll.
| Category | Cap on qualifying cost | Key conditions |
|---|---|---|
| Unconnected subcontractor | 65% of payments made | Work must be qualifying R&D; performed in the UK; contract must cover qualifying activities |
| Connected subcontractor | Lower of: 65% of amount paid, or 65% of connected party's own costs | Related companies (subsidiaries, sister companies); amount claimed is capped at actual underlying cost |
| Externally provided worker (EPW) | 65% of payments to the staff provider | Individual works under your direction and control; supplied by a third-party agency; treated separately from subcontractors |
| Overseas subcontractor | Not eligible (from April 2024) | Narrow exception exists for work not commercially feasible in the UK; geography or conditions must be unique to overseas location; specialist advice required |
The 65% cap for unconnected subcontractors and EPWs is a legislative figure, not an estimate of the R&D proportion. It represents the full claimable amount where the work is confirmed as qualifying R&D. You do not further reduce it by an R&D time percentage unless only part of the subcontractor's work was qualifying.
Contractors operating through their own personal service companies are treated as subcontractors, not as employees. Their costs fall under the subcontractor rules regardless of the day rate or engagement length.
Consumables: What Qualifies and What Does Not
Consumable items used directly and necessarily in R&D qualify as expenditure. The statutory language covers materials or substances that are consumed or transformed in the course of the qualifying R&D activity.
In manufacturing and engineering contexts, qualifying consumables typically include raw materials used to build prototypes, test components that are destroyed in the course of destructive testing, and materials used in iterative experiments that are rendered unusable after each test cycle. In a laboratory or life sciences context, chemicals, reagents, biological materials, and disposable laboratory equipment fall into this category.
For software and digital businesses, consumables are usually a small or nil category. Software development does not typically consume physical materials, and the costs are better captured under staff costs or cloud computing.
The boundary that matters most is the line between the R&D phase and the production phase. Materials used in the R&D process itself qualify; materials used to manufacture the shipped product or deliver the commercial service do not. Where a prototype is later sold or forms part of a commercial delivery, only the proportion attributable to the R&D work qualifies.
HMRC has challenged consumable claims in sectors where the distinction between development activity and commercial production is blurred. Where there is any ambiguity, a clear contemporaneous record linking the materials to specific R&D work rather than production output is essential.
Software Licences and Cloud Computing
Software licences qualify where the software is used directly in the performance of qualifying R&D activities. The test is purposive: the software must be a tool in the R&D process itself, not a general business overhead.
Examples of qualifying software licences include development tooling such as integrated development environments, version control systems, and automated testing frameworks; simulation and modelling software used to test R&D hypotheses; and specialist analytical platforms used as part of the qualifying work.
General business software does not qualify. A Microsoft 365 subscription used across the whole company, accounting software, CRM platforms, and project management tools are overhead costs. They are not R&D expenditure even where R&D staff use them day to day.
Where a single licence is used partly for R&D and partly for other purposes, apportionment is required. The qualifying portion should be calculated on a reasonable and documented basis.
Cloud computing change: April 2023
From April 2023, data and cloud computing costs used directly in qualifying R&D became a separate eligible category of expenditure. This was a significant extension of the relief and benefits companies that run development and testing workloads on cloud infrastructure.
The rule requires the cloud environment to be used for the R&D activity itself. A cloud environment spun up specifically to run R&D workloads, test new algorithms, or develop software features qualifies. The production infrastructure that serves paying customers does not. Where a single cloud account covers both R&D and production workloads, costs should be apportioned by usage and only the R&D proportion claimed.
What Is Excluded
Understanding the exclusions is as important as knowing what qualifies. Claims that include ineligible costs risk triggering HMRC compliance enquiries, which are time-consuming and costly to resolve.
Key exclusions to be aware of
Capital expenditure. The cost of equipment, plant, and machinery does not qualify under R&D relief, even if that equipment is used exclusively for R&D. Capital items may attract separate relief through capital allowances, but the two regimes are distinct.
Production costs. Costs incurred in producing a commercial product or service do not qualify, even where the product itself was developed through qualifying R&D. The relief applies to the development phase only.
Land costs. Payments for land, rights over land, or improvements to land do not qualify.
Patent costs. Filing and maintaining patents is not qualifying R&D expenditure. The separate Patent Box regime exists for companies wishing to benefit from patented innovation.
Overseas subcontractor costs (from April 2024). Work performed by subcontractors overseas is no longer eligible under the merged scheme, subject to a narrow geographical exception. Companies with offshore development teams should take specialist advice on whether the exception applies.
Indirect support staff. HR, finance, marketing, and administrative staff who support the R&D function but do not directly perform qualifying activities do not qualify. The test is whether the individual personally performs or directly supervises qualifying R&D, not whether they work for a company that does R&D.
The Importance of Contemporaneous Records
The Additional Information Form, mandatory since August 2023, requires companies to submit a cost summary broken down by category alongside project descriptions when a claim is filed. This has raised the bar for documentation considerably. HMRC's compliance team uses the AIF to identify claims for closer examination, and a poorly supported cost schedule is one of the signals that attracts scrutiny.
Contemporaneous records are those created at the time the activity took place, not reconstructed after the fact for the purpose of a claim. HMRC distinguishes between the two and is more likely to accept time apportionments that were recorded as part of normal business operations than those pieced together retrospectively.
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1
Maintain project-level time records
Record the time each qualifying employee spends on each R&D project as part of normal operations. Even a simple weekly timesheet categorised by project is adequate. It does not need to be a sophisticated system.
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2
Keep payroll records aligned to R&D periods
Retain payroll summaries showing gross salary, employer NIC, and employer pension contributions for each qualifying employee, broken down by accounting period.
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3
Retain subcontractor invoices and contracts
Keep all invoices and statements of work for subcontractors and EPWs engaged on qualifying R&D. The contract scope should describe the technical work being performed, not just the deliverable.
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4
Document consumable and software purchases
Retain purchase records for consumables and software licences used in R&D. Where a licence covers both R&D and non-R&D use, record the basis for the apportionment.
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5
Link costs to specific R&D projects
The AIF requires costs to be described in the context of the qualifying projects they relate to. Maintaining a mapping between cost categories and project records throughout the year makes preparing the claim substantially easier and more defensible.
Worked Example: Full Cost Build for a 20-Person Engineering Company
To illustrate how these categories combine in practice, consider a 20-person engineering consultancy with an annual turnover of approximately £4 million. Eight members of the technical team spend a portion of their time on a qualifying R&D project to develop a novel structural testing methodology. The company also engages a specialist materials scientist as a subcontractor and uses cloud simulation software.
At the merged RDEC rate of 20%, a company in profit would receive a net benefit of approximately £56,300 against this qualifying expenditure. A loss-making company or one with R&D-intensive operations may receive a different effective benefit depending on their tax position. A specialist adviser will calculate the precise benefit for your specific circumstances.
Note that the example above uses a simplified cost build. In practice, a specialist will work through each employee individually, verify contractor status, confirm consumable usage records, and test cloud cost apportionment against actual usage data.
Frequently Asked Questions
Yes, if the director is directly engaged in qualifying R&D activities. HMRC accepts salary, employer National Insurance contributions, and employer pension contributions for any qualifying employee, including directors. The proportion of time spent on qualifying activities must be documented and defensible. Directors who only manage or oversee the business without directly performing R&D activities do not qualify.
Yes, but with restrictions. Under the merged scheme, you can claim 65% of the cost of unconnected subcontractors engaged on qualifying R&D. For connected subcontractors, different tests apply and the claim is capped at the lower of 65% of what you paid and 65% of the connected party's own costs. Individuals contracting through their own limited companies are treated as subcontractors, not employees.
From April 2023, cloud computing costs used directly in qualifying R&D became a claimable category of expenditure. This includes cloud hosting for development and testing environments, but not production infrastructure serving customers. The environment must be used for the R&D activity itself. Where a single cloud account covers both R&D and production workloads, costs should be apportioned and only the R&D share claimed.
For accounting periods beginning on or after 1 April 2024, subcontractor costs are restricted to work carried out in the UK under the merged scheme. Overseas subcontractor costs are no longer eligible unless they meet a narrow exception for work that is not commercially feasible to perform in the UK. This is a significant change for companies with offshore development teams. A specialist adviser can assess whether the exception applies to your arrangements.
No. Capital expenditure on equipment, plant, and machinery does not qualify under R&D relief, even if that equipment is used exclusively for R&D. Capital items may attract separate relief through capital allowances, but they are treated separately from qualifying R&D expenditure under the relief scheme.
HMRC expects contemporaneous records that can be reviewed during a compliance check. For staff costs this means payroll records and time apportionment evidence such as timesheets or project records. For subcontractors, this means invoices and contracts showing the nature of the work. The Additional Information Form, mandatory since August 2023, requires a cost schedule broken down by category alongside project descriptions. Records should be retained for at least six years after the end of the accounting period to which they relate.
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