UK R&D tax relief now runs through two schemes. For accounting periods beginning on or after 1 April 2024, most companies claim the merged R&D expenditure credit: a 20% credit worth 15p per £1 of qualifying spend at the 25% corporation tax rate, or 16.2p for loss-makers and companies paying tax at 19%. Loss-making SMEs whose relevant R&D expenditure is at least 30% of their total relevant expenditure can claim Enhanced R&D Intensive Support (ERIS) instead, worth up to 26.97p per £1 in cash.
The relief comes with a compliance regime to match. First-time claimants, and companies returning after a gap in claims, must notify HMRC within six months of the end of the period of account, every claim needs an Additional Information Form, and HMRC checked around one in six claims in 2023-24, its latest published figure. This page collects our guides to all of it, each written and reviewed by a chartered adviser.
Start with your situation
New to R&D tax relief. Begin with what counts as qualifying R&D, then which costs qualify, then which scheme applies to your company. Read the claim notification requirement early: for a first claim, the deadline can pass before anyone mentions R&D relief to you.
Already claiming. The rules changed substantially for accounting periods beginning on or after 1 April 2024. Check your position against the merged scheme, and if you hold grant funding, read grant funding and R&D tax relief: the old restrictions are gone, and much of the advice still published online is out of date.
Worried about an enquiry. Start with HMRC R&D enquiries: what to expect, how the process runs and how we defend claims, including claims prepared by other advisers. Enquiry support is included in every LimestoneGrey engagement as standard.
Loss-making and R&D-intensive. You may be entitled to the most generous rate in the system. Read the ERIS guide and test yourself against the 30% threshold with the ERIS intensity calculator.
The schemes
- The merged R&D scheme explained: the 20% credit, the net benefit by tax position, the standard worked example and the PAYE cap.
- Enhanced R&D Intensive Support (ERIS): the 186% deduction, the 14.5% payable credit and how the 30% intensity test really works.
- Which R&D scheme applies to your company?: the decision page, by accounting period start date, profit position and intensity.
- R&D tax relief rates by year: every SME and RDEC rate from 2015 onwards, and what each was worth per £1 of qualifying spend.
- R&D tax relief worked examples: five claims calculated in full — profitable, marginal-rate and loss-making merged scheme, ERIS, and a project that qualifies for nothing.
- HMRC’s R&D statistics, explained: what the annual release measures, the trend lines that matter, and what the latest one showed.
What qualifies
- What counts as qualifying R&D?: the DSIT definition in plain terms: the advance, the uncertainty and the competent professional test.
- Which costs qualify for R&D tax relief?: staff, subcontractors, consumables, software, data and cloud, and what falls outside a claim.
- Grant funding and R&D tax relief: why grants no longer block or reduce relief under the current schemes.
Compliance and deadlines
- The R&D claim notification requirement: the six-month deadline that silently invalidates late first claims.
- The Additional Information Form (AIF): what HMRC requires with every claim and where forms go wrong.
- HMRC R&D enquiries: the process, the timescales honestly stated, and how defensible preparation changes the outcome.
- Backdated claims and the March 2027 deadline: the closing window for claims under the old SME and RDEC schemes.
Contracts and cross-border work
- Contracted-out R&D: who claims?: the intended-or-contemplated test and why contract wording decides the claim.
- Overseas R&D costs under the merged scheme: the UK-only default and the narrow exception for R&D that can only be done overseas.
The rules, sector by sector
The legislation is the same whatever you build, but the arguments that decide a claim are not. Where the boundary falls in software development is a different question from proving an advance in life sciences or biotech, and different again for the contract analysis that runs through aerospace and defence or the trial records behind a manufacturing claim. Our sector guides set out the complication we meet most often in each.
Quick answers and tools
Shorter questions are answered in the FAQ. Terms defined in one line each, with a link to the guide behind every one, are in the R&D tax relief glossary. For working estimates on your own numbers, use the claim value calculator, the ERIS intensity calculator or the claim notification deadline checker — all free, and collected on our tools page.
If you would rather talk than read, talk it through with a chartered adviser. We will tell you which scheme applies, what a claim would involve and whether it is worth making, and the fee is agreed before any work starts.
Position depends on when the accounting period begins, tax position and R&D intensity. The 30% ratio includes connected companies.
Written by Matthew Jones ACA CTA. Last reviewed August 2026.
