R&D tax relief in 2026 looks materially different from the regime that operated a few years ago. The merged scheme is now the default for most claimants, the Enhanced R&D Intensive Support (ERIS) regime sits alongside it for a specific tranche of loss-making SMEs, and the procedural overlay - the additional information form, pre-notification, and the named senior officer requirement - has fundamentally changed the discipline required to make a defensible claim.
HMRC has also continued to invest in compliance activity in this area. Enquiry rates are higher than they were five years ago, and the cost of a poorly supported claim has risen - both in terms of disallowed relief and in terms of penalties for careless or deliberate inaccuracies.
This guide sets out the position for UK accountancy firms advising on R&D claims in 2026: the structure of the merged scheme, the eligibility tests, the procedural requirements, the qualifying expenditure rules, and the practical workflow that produces claims that hold up to HMRC scrutiny.
The merged scheme in outline
For accounting periods beginning on or after 1 April 2024, the merged scheme replaces the historic SME and RDEC regimes for most claimants. The merged scheme operates as an above-the-line expenditure credit at a headline rate of 20%, which is then taxable, producing a net benefit broadly comparable to the previous RDEC rate but available to all eligible claimants regardless of size (subject to the ERIS exception described below).
The mechanics are essentially the previous RDEC mechanics extended to the SME population: the credit is recognised as a trading receipt above the tax line, then offset against the company's tax liability or paid out through a step-down formula where the company is loss-making.
The ERIS regime for loss-making intensive SMEs
A specific exception remains for loss-making SMEs whose R&D intensity (qualifying R&D expenditure as a proportion of total expenditure) exceeds the threshold set by the relevant Finance Act. The threshold was reduced from 40% to 30% for accounting periods beginning on or after 1 April 2024, broadening the population of companies that can access the more generous ERIS rates.
ERIS provides a 186% deduction on qualifying expenditure, with the resulting loss surrenderable for a payable tax credit at 14.5% - a meaningful enhancement over the merged scheme position for the eligible cohort. Many early-stage software, biotech, and clean technology companies fall within ERIS, and the conversation at the planning stage is often about how to structure intra-group cost allocations to remain within the regime.
What qualifies as R&D for tax purposes
The technical test for R&D follows the BIS Guidelines (now BEIS, formerly DTI) on the meaning of R&D for tax purposes. The work must seek an advance in science or technology, involve the resolution of scientific or technological uncertainty that could not be readily resolved by a competent professional in the field, and be aimed at the overall field of knowledge - not merely the company's own commercial position.
In practice, the qualifying boundary sits somewhere between routine engineering and breakthrough innovation. Day-to-day software bug fixing does not qualify. Building a novel distributed algorithm where the existing literature does not provide a clear solution may qualify. The professional judgement of the technical lead is critical, and the file should record the reasoning rather than asserting eligibility as a conclusion.
Qualifying expenditure categories
The qualifying expenditure categories under the merged scheme are broadly:
- Staffing costs of employees engaged in qualifying R&D activity, apportioned by the proportion of their time spent on qualifying work
- Externally provided workers, subject to the contracted-out work rules introduced in recent Finance Acts
- Subcontracted R&D, where the contractor undertakes part of the qualifying activity on the company's behalf
- Software and consumables used directly in the R&D
- Cloud computing and data licence costs, included since the Finance Act 2023 reforms
- Payments to clinical trial volunteers (specific to relevant sectors)
The additional information form
For accounting periods beginning on or after 1 August 2023, every R&D claim must be supported by an additional information form (AIF) submitted to HMRC before the claim is filed in the Corporation Tax return. The AIF is the principal vehicle by which HMRC understands what the company has claimed for, who did the work, and why it qualifies.
Treat the AIF as the primary deliverable of the claim engagement. A well-drafted AIF, with clear project narratives, a properly costed expenditure analysis, and a credible competent professional sign-off, materially reduces enquiry risk. A poorly drafted AIF substantially increases it.
Pre-notification for first-time claimants
Companies making an R&D claim for the first time, or for the first time in three years, must pre-notify HMRC of the intention to claim within six months of the end of the accounting period to which the claim relates. Failure to pre-notify within the window typically results in the claim being disallowed in full - there is no informal grace period.
A clean workflow puts the pre-notification check in the engagement onboarding process. Where a company has not made an R&D claim in the preceding three accounting periods, the pre-notification is filed within the first quarter after the relevant period end, well within the six-month window.
The named senior officer
Each claim must identify a named senior officer of the company who takes responsibility for the claim. Each claim must also identify the agent who prepared the claim, including the agent's contact details and (for the firm) any internal sign-off. These requirements were introduced to address the concerns about so-called R&D boutiques that filed high volumes of poorly supported claims.
For accounting firms, the named senior officer requirement aligns naturally with the way most reputable practices already operate. The discipline now is to ensure the supporting file evidences the partner-level review and that the engagement letter records the agent's position correctly.
HMRC enquiry profile and defensive file build
HMRC enquiry rates in R&D have risen materially over the last several years. A claim that meets all the procedural requirements (AIF, pre-notification, named officer) and is supported by a substantive narrative grounded in the BIS Guidelines is materially less likely to attract enquiry than a claim that meets the form requirements alone.
A defensive file should include the project narratives, the competent professional's technical statement, the staff time apportionment working papers, the costed expenditure analysis, the engagement letter and risk assessment, and a partner-level sign-off memo. The cost of building this file is real, but it is dwarfed by the cost of defending an enquiry against a claim that lacks it.
Common pitfalls in 2026
Recurring problems include: time apportionment that cannot be reconciled to project plans; subcontract work that has been treated as qualifying expenditure but does not meet the new contracted-out rules; competent professional sign-offs that are signed by the company's commercial director rather than a person with the relevant technical authority; and claims where the company's own product roadmap, written for marketing purposes, contradicts the technical narrative submitted to HMRC.
The mitigation is to align the technical narrative with the company's own contemporaneous documentation. If the claim says the work was a novel solution to a known technical problem, the company's internal documents should support that characterisation - they will be the first thing an enquiry inspector asks to see.
How Accupe supports R&D claim work
Accupe gives firms a structured workspace for R&D engagements. The AI document analyser reads project documents, board papers, and timesheets with source citation, surfacing the evidence that supports the technical narrative. Smart Boards track every claim through pre-notification, AIF preparation, partner review, and CT600 submission. The client portal handles secure exchange of supporting documents, e-signatures handle the named senior officer sign-off, and Compliance Radar tracks the engagement risk alongside the rest of the client portfolio. Where a firm runs a substantial R&D book, the structure is what keeps the work scalable and the files defensible.