R&D Tax Credits for UK Startups: What Qualifies and How to Claim

R&D tax credits turn technical work into cash. If your startup builds a product, writes code, or solves engineering problems, you may already qualify. Yet many founders miss out or file weak claims.

The issue is not awareness, it’s execution. The merged R&D tax relief scheme changed the rules from April 2024. The R&D advance notification requirement adds a strict deadline. And small errors,  wrong costs, poor narrative, missed forms, can invalidate a valid R&D tax claim.

This guide explains R&D tax credits in the UK in clear terms. You’ll see what qualifies, how the research and development tax credit works, and how to claim it step by step. We’ll also cover the new scheme, common mistakes, and a real r&d tax credit calculation example UK founders can use.

What are R&D tax credits?

R&D tax credits are a UK government incentive that allows companies to reduce their Corporation Tax bill or receive a cash payment from HMRC in exchange for qualifying research and development expenditure. Under the merged scheme introduced in April 2024, most UK companies receive an above‑the‑line credit of 20% on qualifying costs, with R&D‑intensive startups qualifying for a higher rate of 27% via enhanced support.

How the UK R&D tax credit scheme works

The R&D tax credits scheme rewards companies that invest in innovation. When a project seeks an advance in science or technology, the activities that directly contribute to resolving that scientific or technological uncertainty are eligible for research and development tax credit relief. Qualifying indirect activities (administration, security, feasibility studies) also count.

Since 1 April 2024, the SME and RDEC programmes have been merged. A unified R&D expenditure credit (RDEC) applies to all companies. It is taxable and appears “above the line” in accounts, boosting EBITDA before being taxed at the corporation tax rate. The credit rate is 20% of qualifying expenditure. R&D‑intensive startups, those spending 30% or more of total costs on R&D, can instead claim enhanced support (ERIS). Loss‑making companies can surrender their losses to HMRC for a payable credit worth up to 14.5% of the surrenderable loss. You can’t claim under both the merged RDEC scheme and ERIS for the same expenditure.

How much can a UK startup actually get back?

Under the merged R&D tax relief scheme, a profitable company claiming £100,000 of eligible spend would record a £20,000 R&D credit. After paying corporation tax (25% for most startups), the net benefit is roughly £15 000. A loss‑making R&D‑intensive startup spending £150,000 could claim an ERIS credit worth 27% (i.e. £40,500). Because ERIS credits are payable rather than taxable, the startup receives the full £ 40,500 in cash, subject to the PAYE cap (£20,000 + 300% of PAYE and NIC liabilities).

The merged R&D scheme: what changed in April 2024

In April 2024, HMRC replaced the SME and RDEC regimes with a single merged R&D expenditure credit scheme. The new approach aligns relief for all companies and eliminates many quirks of the old dual system.

SME scheme vs. RDEC: what existed before

Before April 2024, small and medium‑sized enterprises could claim enhanced deductions of 86% and, if loss‑making, surrender losses for a cash credit worth 10% to 14.5% of the surrenderable loss. Large companies used the RDEC, an above‑the‑line credit of 20%. There were different rules for subcontractor costs and subsidised projects. The merger simplified the system.

What the merged scheme means for your startup

Under the merged scheme, your company receives a 20% R&D credit on qualifying expenditure. The credit counts as trading income and is taxable at the corporation tax rate. If the credit exceeds your PAYE/NIC cap, the excess is carried forward. You no longer need to check if a project has been subsidised; the merged scheme removes the restriction on subsidised costs. To claim, you must file a technical narrative and cost breakdown through the additional information form (discussed later).

The R&D‑intensive startup scheme (if your R&D spend is 30%+ of total costs)

ERIS is a bolt‑on for loss‑making R&D intensive startups. To qualify, R&D expenditure must be at least 30% of total expenditure. Instead of a taxable credit, you get an enhanced deduction of 86% plus a payable credit worth up to 14.5% of the surrenderable loss. Your credit is not taxed and can be paid out as cash, subject to the PAYE cap. If you meet the intensity condition in your last accounting period and continue to invest heavily, you may remain eligible even if R&D spend drops slightly.

Does your startup qualify for R&D tax credits?

Claiming R&D tax credits begins by answering a simple question: Does your project count as R&D? HMRC’s definition is intentionally strict.

The HMRC definition of qualifying R&D

For tax purposes, R&D occurs when a project seeks an advance in science or technology. The work must extend overall knowledge or capability in a field, not just your company’s understanding. Activities that directly contribute to resolving scientific or technological uncertainty qualify, along with certain indirect activities such as feasibility studies, administration and equipment maintenance.

What counts as an advance in science or technology

An advance is an improvement in overall knowledge or capability; adapting a technology from another field also counts if the adaptation isn’t obvious. The work can produce tangible outcomes (a cleaner chemical process) or intangible outcomes (more reliable software). The project remains R&D even if the advance isn’t achieved. Scientific or technological uncertainty exists when a competent professional cannot readily resolve whether the objective is possible or how to achieve it. Routine optimisation or duplication of existing products without a material change does not qualify.

What does not qualify (common founder mistakes)

HMRC does not accept projects that rely on existing knowledge without innovation. Routine software updates, commercial trials, market research, aesthetic design changes and support activities without a technological challenge fall outside the scope. You also can’t claim for the production and distribution of goods, capital expenditure, rent, the cost of land, patents or trademarks. Startups often misclassify business-as-usual costs or confuse product development with research and development tax relief. The technical narrative must demonstrate the uncertainty faced and why the solution wasn’t obvious.

What costs can you claim?

Qualifying costs vary by category. Understanding each cost heading helps maximise your R&D tax claim and avoid disallowed items.

Staff wages and salaries

Salaries, wages, bonuses, pension contributions, and secondary Class 1 National Insurance contributions for staff directly engaged in R&D can be claimed. You can apportion costs based on the percentage of time spent on qualifying activities: if a developer spends 80% of their time on the project, 80% of their pay is eligible. For staff carrying out supporting activities (human resources to recruit researchers, specialist cleaning for a lab), you can claim a proportion of their costs.

Subcontractors and freelancers

For periods after April 2024, the contracting rules changed. Only the company that decides to undertake the R&D can claim. If a subcontractor is connected (e.g. a group company), you can claim the lower of 100% of the payment or the contractor’s relevant costs. For unconnected contractors, you can claim 65% of the payment. You cannot claim costs for R&D activity performed overseas unless you meet narrow exceptions. Externally provided workers supplied by an agency are treated similarly: you can claim 65% of payments for unconnected providers.

Software and cloud computing costs

Licence fees for software used in R&D are eligible. You can also claim a reasonable share of costs for software partly used in R&D. Since April 2023, data licences and cloud computing costs (storage, hardware, operating systems and platforms) are qualifying expenditure. You must exclude costs relating to indirect activities such as sales or marketing.

Consumables and materials

Consumable items are materials used up in the project: fuel, chemicals, power and water. Only the proportion consumed in R&D is claimable. If you sell or transfer ownership of these items, the cost cannot be claimed.

R&D tax credits for software development specifically

Software companies often qualify because developing novel algorithms, architectures or processing techniques involves technological uncertainty. Qualifying costs include developer salaries, cloud infrastructure, data licences, testing environments and prototype consumables. Routine bug fixing or adapting off‑the‑shelf frameworks without innovation does not qualify. Document the uncertainty (e.g. performance at scale, concurrency issues, data processing challenges) and how your team resolved it.

The HMRC Advance notification requirement

In 2023, HMRC introduced a claim notification rule to curb abuse. Many founders miss this step and lose their R&D tax credit.

Who must notify HMRC before claiming

If you’re claiming R&D tax relief or the RDEC for accounting periods starting on or after 1 April 2023, you must submit a claim notification form if either: (a) it’s your first claim, or (b) your last claim was more than three years before the end of the notification period. Established claimants who filed within the past three years are exempt.

The 6‑month deadline and how to submit

Your claim notification period begins on the first day of your financial year (period of account) and ends six months after the end of that period. For example, if your financial year is 1 January 2025 to 31 December 2025, you must notify HMRC between 1 January 2025 and 30 June 2026.

Submit the online notification form via your Government Gateway. You’ll need your company’s Unique Taxpayer Reference, contact details of the senior R&D contact, and a high‑level description of planned activities. HMRC will email you a reference number. If you miss the deadline and haven’t claimed in the last three years, your r&d tax credits claim will be invalid. Always diarise the date; Undo Capital’s cap table platform includes reminders for key tax deadlines to help avoid this mistake.

How to claim R&D tax credits: step by step

A robust claim requires more than filling in a form. You must gather technical evidence, allocate costs correctly and file the claim through the correct channels.

Step 1: Prepare your R&D technical narrative

The technical narrative explains how your project meets HMRC’s definition of R&D. It should outline the scientific or technological advance sought, the uncertainty faced, the methods used to overcome it, and why the outcome wasn’t obvious to a competent professional. Include project timelines and highlight the roles of key staff. Avoid marketing language; focus on the problem and the work done.

Step 2: Calculate your qualifying R&D expenditure

Gather payroll records, invoices and internal timesheets. Allocate staff costs based on time spent on qualifying activities. Include consumables, software licences, cloud computing costs and subcontractor payments according to the rules above. Exclude disallowed items (rent, patents, capital expenditure). Keep detailed records to substantiate allocations. If you’re claiming ERIS, calculate your R&D intensity (qualifying expenditure ÷ total expenditure) to confirm it exceeds 30%.

Step 3: Complete the additional information form

HMRC now requires an additional information form for each accounting period. The form must be submitted before or at the same time as your CT600; if you send the tax return first, HMRC will reject the claim. The form asks for company details, R&D intensity, description of each project, costs by category and the technical narrative. This is separate from the claim notification; both may be required.

Step 4: File your CT600 Corporation Tax Return with HMRC

Next, prepare your Corporation Tax return (CT600). Include the R&D expenditure credit under the correct box (Box L on the CT600 for the merged scheme) and attach the computations. File through HMRC’s online portal or via your accountant. Ensure the figures reconcile with the additional information form and that any tax payable after the credit is paid on time.

Step 5: Receive your tax credit or cash payment

Once HMRC processes your claim, the R&D credit will either reduce your corporation tax bill or be paid as cash if you surrender losses. HMRC typically processes claims in four to eight weeks, though complex claims can take longer. If HMRC needs clarification, it will open an enquiry. Keep your records ready. Under ERIS, the cash payment will be credited to your bank account after the claim is approved.

Common mistakes UK startups make when claiming R&D tax credits

Most rejected R&D tax credit claims fail for the same four reasons, and all of them are avoidable with the right preparation.

Claiming costs that do not qualify

Many first‑time filers include non‑R&D costs such as marketing, admin salaries unrelated to the project, patent filing fees or capital equipment. HMRC will disallow these. Use the qualifying cost categories and exclude disallowed items like patents, rent and production costs.

Missing the advance notification deadline

A frequent pitfall is forgetting to submit the claim notification form within six months after your accounting period ends. Without this notification, HMRC will reject your claim. Use reminders or software tools (Undo Capital’s platform includes deadline tracking) to ensure you meet the notification deadline.

Weak technical narrative rejected by HMRC

HMRC expects a concise but detailed technical narrative explaining the scientific or technological uncertainty and why the project constitutes R&D. Generic marketing copy or a focus on commercial benefits leads to enquiries. Document the specific challenge, your methodology and the outcome. Use the guidelines on what constitutes an advance.

Not keeping adequate records

HMRC may ask for timesheets, payroll records, invoices and technical documents. Poor record‑keeping undermines your claim. Use project management tools to track time spent on each work package. Maintain a file for each qualifying project containing design documents, test results and evidence of uncertainties encountered. Undo Capital’s cap table and documentation management helps store these records in a single place, making audits easier.

How R&D tax credits connect to your cap table and equity planning

R&D tax credits aren’t just a tax break; they directly affect your runway and dilution. Cash received via the merged RDEC or ERIS reduces the need for immediate equity funding, allowing you to push a fundraising round back by several months. A larger runway gives you leverage to negotiate better terms with investors and minimise dilution. Conversely, overestimating the credit and planning to spend it can leave you short if HMRC reduces your claim.

Undo Capital’s cap table management platform integrates expected R&D credit receipts into your financial model. By forecasting cash inflows from R&D tax credit and SEIS/EIS capital, you can align fundraising with milestone achievements. The tool includes reminders for claim notification deadlines and CT600 filing dates, and automatically updates your cap table when R&D credits are received. It helps founders model dilution scenarios so they can decide whether to take a loan against future R&D credit or raise equity.

Learn more in Undo Capital’s detailed guide on how SEIS and EIS work and SEIS/EIS advance assurance service.