What Is R&D Tax Relief? A Complete Guide for UK Businesses

R&D tax relief is a UK government incentive that allows companies to reduce their corporation tax liability — or, if loss-making, receive a direct cash payment — in recognition of money spent on qualifying research and development activity. It is administered by HMRC and was originally introduced in 2000 to encourage innovation among small and medium-sized businesses. Today it applies to companies of all sizes across almost every sector, from software and biotech to advanced manufacturing, medical devices, and engineering services.

The relief exists because genuine R&D is economically valuable but commercially risky. Many projects fail, or take far longer and cost far more than anticipated. The government’s position is that the country benefits when companies take on that risk — so it shares a portion of the cost through the tax system. For businesses willing to navigate the claim process, the financial returns are significant.

The Two Current Schemes

For accounting periods beginning on or after 1 April 2024, the UK operates two R&D schemes. The landscape was significantly simplified by HMRC’s April 2024 reforms, which merged the old SME and RDEC schemes into a single system:

• The Merged Scheme — the default scheme for the vast majority of companies. It delivers a 20% above-the-line R&D Expenditure Credit (RDEC) on qualifying expenditure. In practical terms, a company spending £100,000 on qualifying R&D will receive a £20,000 gross credit, which offsets its corporation tax liability. After the standard 25% corporation tax rate, the net benefit works out to approximately £15,000 per £100,000 spent. Importantly, because the credit is “above the line”, it is visible in the profit-and-loss account, making it easier to budget for and explain to investors.
• Enhanced R&D Intensive Support (ERIS) — a more generous scheme specifically for loss-making SMEs that spend at least 30% of their total expenditure on R&D. Qualifying companies receive a 27% credit — broadly equivalent to the old SME scheme’s headline benefit. For a loss-making startup spending heavily on R&D, this equates to approximately £27 of net cash benefit per £100 spent, delivered as a payable credit even where no tax is owed.

Understanding which scheme applies to your business is the essential first step. If you are loss-making and R&D-intensive, it is worth checking ERIS eligibility carefully before assuming the merged scheme applies — the difference in value can be material.

Who Qualifies for R&D Tax Relief?

To claim R&D tax relief, your company must meet three core conditions:

• Be a UK limited company subject to corporation tax
• Have carried out qualifying R&D activities during the accounting period
• Have incurred actual costs directly related to that R&D

Sole traders, partnerships, and LLPs are not eligible. Nor are companies that have not yet commenced trading. There is no minimum spend threshold, though claims below around £15,000 of qualifying expenditure may not be cost-effective to prepare without efficient tooling. Sector does not matter: software companies, manufacturers, food producers, and professional services firms have all made successful claims.

What Counts as Qualifying R&D?

HMRC follows the definition of R&D set out in the Department for Science, Innovation and Technology (DSIT) guidelines. In plain terms, qualifying R&D is work that seeks to achieve an advance in overall knowledge or capability in a field of science or technology, by resolving a scientific or technological uncertainty that a competent professional in the field could not readily resolve.

Crucially, “advancing science or technology” does not mean you need to be doing academic research or publishing papers. It means your work goes beyond what is currently publicly known — that a skilled practitioner in the field could not simply look up the answer. Common qualifying examples include:

• Building a novel machine-learning model where existing approaches did not meet performance or accuracy requirements
• Developing a new real-time data processing pipeline capable of handling a scale or throughput for which no commercially available solution existed
• Designing hardware or firmware architecture to overcome specific thermal, power, or latency constraints
• Creating a new algorithm to solve a combinatorial problem that standard techniques could not address within required performance bounds
• Developing a new pharmaceutical formulation or medical device where the biological or material behaviour was not predictable from existing knowledge

Importantly, failed projects still qualify. If your team attempted to resolve a genuine technical uncertainty and the project was abandoned, the costs incurred during that work are still eligible. The relief rewards the attempt, not just the outcome.

What Costs Qualify?

The following categories of expenditure are eligible under the merged scheme:

• Staff costs — typically the largest category. Includes gross salaries, employer’s National Insurance contributions, and employer pension contributions for employees directly engaged in qualifying R&D. Where an employee splits their time between R&D and non-R&D work, only the qualifying proportion of their costs can be claimed. Accurate time-tracking records are important.
• Subcontractors and externally provided workers (EPWs) — costs paid to third parties to carry out R&D on your behalf, or staff supplied through an agency. Under the merged scheme, overseas contractor costs are generally restricted: they only qualify where there is a specific geographic or regulatory reason why the work can only be done abroad.
• Consumables and materials — materials used up or transformed in the direct course of R&D activity. Prototype materials, test components, and laboratory supplies commonly fall into this category.
• Software licences — the proportion of software licence costs that is attributable to qualifying R&D activity, where the software is used directly in that work.
• Cloud computing and data costs — included since April 2023. Payments for cloud compute, data storage, and licensed data sets used directly in qualifying R&D activity now qualify. This is particularly relevant for companies training large models or running high-throughput simulations.

How Much Can You Claim?

The benefit you receive depends on the scheme you fall under and your tax position. Here are concrete examples:

• Merged scheme — profit-making company: £100,000 qualifying spend → £20,000 gross RDEC credit, reducing your corporation tax bill. Net benefit after 25% tax on the credit: approximately £15,000.
• Merged scheme — loss-making company: £100,000 qualifying spend → £20,000 gross credit. Where the company has no tax liability, the credit can be offset against other PAYE/NIC liabilities or, in some cases, paid out as cash — subject to the PAYE cap rules.
• ERIS — loss-making R&D-intensive SME: £100,000 qualifying spend → approximately £27,000 net cash benefit, paid directly by HMRC even where the company has no tax liability. For a pre-revenue startup spending substantially all of its budget on R&D, this can be a meaningful contribution to runway.

The Claim Process

A well-prepared R&D claim follows five key steps:

1. Identify qualifying activities — work with your technical team to identify which projects and specific tasks involved genuine scientific or technological uncertainty. This is often harder than it sounds; engineers describe their work in engineering terms, not HMRC terms.
2. Calculate qualifying costs — for each qualifying project, apportion staff time and calculate the associated salary, National Insurance, and pension costs. Add subcontractor, software, consumable, and cloud costs where applicable.
3. Prepare technical narratives — HMRC requires a written explanation of each qualifying project covering: the scientific or technological advance sought, the uncertainties encountered, and how your team worked to resolve them. This is typically the most time-consuming part of the claim process.
4. Submit the Additional Information Form (AIF) — mandatory since August 2023, the AIF must be submitted to HMRC online before (or at the same time as) the corporation tax return. It captures project descriptions, qualifying expenditure by category, and contact details for the responsible officer. A claim submitted without a corresponding AIF will be rejected automatically.
5. File with the corporation tax return — the R&D expenditure credit figures are entered in the CT600 return. Your accountant or tax adviser will handle the actual CT600 submission.

Claims can be made up to two years after the end of the accounting period in which the R&D took place. If your business has been doing qualifying work for several years but has never claimed, it may be possible to submit retrospective claims for prior periods — subject to the two-year time limit.

How Menlo Helps

The two most labour-intensive parts of an R&D claim — identifying qualifying work and writing the technical narratives — are exactly what Menlo automates. By connecting directly to your source control system, Menlo analyses your engineering activity across the claim period, maps it to HMRC’s qualifying criteria, and generates draft technical narratives ready for your review. The result is a faster, better-evidenced claim that is substantially less disruptive to your engineering and finance teams.

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