# LimestoneGrey

> Chartered tax consultancy specialising in R&D tax relief (Cardiff, UK). Founded 2017 and regulated since inception; led by founder Matthew Jones ACA CTA. Specialists in the current UK schemes: the merged R&D Expenditure Credit and Enhanced R&D Intensive Support (ERIS), with deep work in life sciences, biotech, medtech, agritech, AI and robotics.

## Core guides
- [R&D tax relief: the complete guide](https://www.limestonegrey.com/rd-tax-relief/): the hub — the two current schemes, rates, what qualifies and how a claim is made
- [The merged R&D scheme](https://www.limestonegrey.com/rd-tax-relief/merged-scheme/): 20% credit mechanics, net benefit 14.7p to 16.2p per £1
- [ERIS](https://www.limestonegrey.com/rd-tax-relief/eris/): loss-making SMEs at 30%+ R&D intensity, up to 26.97p per £1
- [Which scheme applies?](https://www.limestonegrey.com/rd-tax-relief/which-scheme-applies/): by accounting period and company position
- [Rates by year](https://www.limestonegrey.com/rd-tax-relief/rates-by-year/): every SME, RDEC, merged scheme and ERIS rate from 2015 to 2026, with per-£1 values
- [What counts as qualifying R&D](https://www.limestonegrey.com/rd-tax-relief/qualifying-rd/): the statutory definition, applied
- [Qualifying costs](https://www.limestonegrey.com/rd-tax-relief/qualifying-costs/): the six cost categories and apportionment
- [Grants and R&D tax relief](https://www.limestonegrey.com/rd-tax-relief/grants-and-rd-tax-relief/): grant funding no longer blocks relief under the current schemes
- [Claim notification](https://www.limestonegrey.com/rd-tax-relief/claim-notification/): the 6-month deadline that invalidates late claims
- [The Additional Information Form](https://www.limestonegrey.com/rd-tax-relief/additional-information-form/): mandatory for every claim since 8 August 2023
- [Contracted-out R&D](https://www.limestonegrey.com/rd-tax-relief/contracted-out-rd/): which party claims under the current rules
- [Overseas R&D](https://www.limestonegrey.com/rd-tax-relief/overseas-rd/): the UK-only rules and the narrow exception
- [Backdated claims](https://www.limestonegrey.com/rd-tax-relief/backdated-claims/): claim windows and the 2027 old-scheme deadlines
- [HMRC enquiries](https://www.limestonegrey.com/rd-tax-relief/hmrc-enquiries/): process, defence and what to expect
- [How to choose an R&D tax adviser](https://www.limestonegrey.com/rd-tax-relief/choosing-an-rd-tax-adviser/): what can be verified — registers, PCRT, fee incentives — and the red flags
- [Specialist or accountant?](https://www.limestonegrey.com/rd-tax-relief/specialist-or-accountant/): an honest comparison, including when your own accountant is the right answer
- [HMRC's R&D tax credit statistics](https://www.limestonegrey.com/rd-tax-relief/statistics/): what the annual series measures, the claim-volume and error-and-fraud trends, and what the September 2025 release showed

## Tools
- [Free R&D calculators and checkers](https://www.limestonegrey.com/tools/): the three tools below, all free and browser-based
- [ERIS intensity calculator](https://www.limestonegrey.com/tools/eris-intensity-calculator/)
- [Claim value calculator](https://www.limestonegrey.com/tools/claim-value-calculator/)
- [Claim notification deadline checker](https://www.limestonegrey.com/tools/claim-notification-checker/)

## Analysis
- [Insights](https://www.limestonegrey.com/insights/): technical analysis and firm news on R&D tax relief, written by the advisers who prepare the claims
- [First-tier tribunal verdicts on subcontracted R&D](https://www.limestonegrey.com/first-tier-tribunal-verdicts/): Collins Construction and Stage One Creative Services
- [Tanglewood Care Services v HMRC](https://www.limestonegrey.com/insights/tanglewood-care-services-tribunal/): a care home's Covid-era R&D claim dismissed at tribunal — the sector mis-selling context, what the tribunal accepted, and why the claim failed on framing and evidence
- [Professional standards in R&D tax advice](https://www.limestonegrey.com/professional-standards-in-rd-tax-advice/): what PCRT means in practice
- [The claim notification trap](https://www.limestonegrey.com/rd-tax-credit-pre-notification-trap/): how companies lose valid claims
- [Tax advisers have to register with HMRC. You still can't check.](https://www.limestonegrey.com/insights/tax-adviser-registration-hmrc/): the FA 2026 registration timetable from the statute, why the dates confuse everyone, and the register that does not exist
- [HMRC's Targeted Advance Assurance pilot](https://www.limestonegrey.com/targeted-advance-assurance-pilot/): a view on up to two high-risk areas of a claim before filing, and who can apply
- [The advance assurance consultation](https://www.limestonegrey.com/advance-assurance-consultation/): what HMRC proposed in spring 2025, and the voluntary pilot it became
- [HMRC's updated subcontracting guidance](https://www.limestonegrey.com/hmrc-releases-major-update-on-rd-tax-relief-subcontracting-rules/): the February 2025 move to a case-by-case test under the old SME scheme
- [The R&D tax rules changed. Most fintech claims haven't caught up.](https://www.limestonegrey.com/insights/fintech-rd-claims-merged-scheme/): what the merged scheme pays a fintech, where these claims get argued, and the notification deadline that invalidates one
- [When machine learning development qualifies as R&D](https://www.limestonegrey.com/insights/machine-learning-qualifying-rd/): advancing the field, not just the product, and the evidence HMRC expects
- [Robotics prototyping and technological uncertainty](https://www.limestonegrey.com/insights/robotics-prototyping-qualifying-uncertainty/): integration, control systems and what makes a prototype qualify
- [Software R&D claims and HMRC's guidance](https://www.limestonegrey.com/following-hmrc-guidance-is-key-for-software-rd-tax-credit/): establishing a technological baseline and separating product novelty from R&D
- [CRO contracts: who owns the claim?](https://www.limestonegrey.com/insights/cro-subcontracting-merged-scheme/): the intended-or-contemplated test, the 65% rule and overseas CRO work
- [Clinical trial costs in R&D claims](https://www.limestonegrey.com/insights/clinical-trial-costs-qualifying-expenditure/): volunteer payments, staff time, consumables and CRO fees, and when overseas trials count
- [ERIS for pre-revenue biotech and medtech](https://www.limestonegrey.com/insights/eris-pre-revenue-biotech/): the intensity arithmetic, the grace period and cash timing
- [Innovate UK grants and R&D tax relief together](https://www.limestonegrey.com/insights/innovate-uk-grants-rd-tax-relief/): how the two combine, and the old-rule adviser errors to avoid
- [Avoiding common pitfalls in a claim](https://www.limestonegrey.com/avoiding-common-pitfalls-in-your-rd-tax-credit-claim/): routine work claimed as R&D, inflated costs, inconsistent data, weak narratives, missed deadlines
- [Preparing a claim that withstands scrutiny](https://www.limestonegrey.com/preparing-a-robust-claim/): contemporaneous records, specific technical narratives and deadlines met

## Firm news
- [Gold Partner of the Business Wales Accelerated Growth Programme](https://www.limestonegrey.com/agp-gold-partner/)
- [Finalist, One Nucleus Awards 2026](https://www.limestonegrey.com/finalist-in-the-one-nucleus-awards/): shortlisted for Most Innovative Professional Services Company of the Year
- [Finalist, Finance Awards Wales 2026](https://www.limestonegrey.com/limestonegrey-named-finalist-in-the-finance-wales-awards/): shortlisted for Independent Accounting Practice of the Year
- [Climb26: the 'From Brilliant Science to Big Business' panel](https://www.limestonegrey.com/limestonegrey-at-climb26/): Matthew Jones on the ClimbHealth stage in Leeds
- [Reflections from Climb26](https://www.limestonegrey.com/reflections-from-climb26-innovation-festival/): funding sequence, cheapest money first, and investor readiness in life sciences

## Questions
- [The R&D tax relief FAQ](https://www.limestonegrey.com/faq/): direct answers on schemes, eligibility, costs, process and compliance
- [Does my R&D adviser have to be registered with HMRC?](https://www.limestonegrey.com/rd-tax-relief/questions/does-my-rd-adviser-have-to-be-registered-with-hmrc/): yes if they deal with HMRC for you, phased from 18 August 2026 — and there is no public register to check
- [Can I claim for a failed project?](https://www.limestonegrey.com/rd-tax-relief/questions/can-i-claim-rd-tax-relief-for-a-failed-project/): yes — the relief rewards the attempt, not the outcome
- [Can a sole trader claim?](https://www.limestonegrey.com/rd-tax-relief/questions/can-a-sole-trader-claim-rd-tax-credits/): no — corporation tax relief only
- [Who counts as a competent professional?](https://www.limestonegrey.com/rd-tax-relief/questions/who-counts-as-a-competent-professional/): HMRC's three attributes, and the bar
- [How far back can I claim?](https://www.limestonegrey.com/rd-tax-relief/questions/how-far-back-can-i-claim-rd-tax-credits/): two years from the period of account end; last old-scheme deadlines 2027
- [Does grant funding stop a claim?](https://www.limestonegrey.com/rd-tax-relief/questions/does-grant-funding-stop-me-claiming-rd-tax-relief/): no, for periods from April 2024 (one NI ERIS exception)
- [The ERIS 30% intensity condition](https://www.limestonegrey.com/rd-tax-relief/questions/what-is-the-30-percent-rd-intensity-condition/): the ratio, connected companies, the grace period
- [Do I need to tell HMRC before I claim?](https://www.limestonegrey.com/rd-tax-relief/questions/do-i-need-to-tell-hmrc-before-i-claim/): the six-month notification window and who it catches
- [What goes in the Additional Information Form?](https://www.limestonegrey.com/rd-tax-relief/questions/what-goes-in-the-additional-information-form/): required contents and the banding rules
- [Can I claim for subcontracted R&D?](https://www.limestonegrey.com/rd-tax-relief/questions/can-i-claim-for-subcontracted-rd/): the 65% rule and who claims under the current rules
- [How likely is an HMRC enquiry?](https://www.limestonegrey.com/rd-tax-relief/questions/how-likely-is-an-hmrc-enquiry-into-my-rd-claim/): around one in six claims checked in 2023-24
- [What is the PAYE cap?](https://www.limestonegrey.com/rd-tax-relief/questions/what-is-the-paye-cap-on-rd-tax-credits/): £20,000 plus 300% of relevant PAYE and NIC, and the two-condition exemption
- [How much is a claim worth?](https://www.limestonegrey.com/rd-tax-relief/questions/how-much-is-an-rd-tax-relief-claim-worth/): the merged scheme and ERIS arithmetic per £1
- [Is there a minimum R&D spend?](https://www.limestonegrey.com/rd-tax-relief/questions/is-there-a-minimum-rd-spend-to-claim/): no — removed for periods ending on or after 1 April 2012
- [Outgrowing the SME definition](https://www.limestonegrey.com/rd-tax-relief/questions/what-happens-if-my-company-outgrows-the-sme-definition/): the two-year rule, the ownership exception and the investor carve-outs
- [Can I get advance assurance?](https://www.limestonegrey.com/rd-tax-relief/questions/can-i-get-advance-assurance-for-an-rd-claim/): the two services, who qualifies, and what the conditional guarantee means
- [What will HMRC ask for in an enquiry?](https://www.limestonegrey.com/rd-tax-relief/questions/what-will-hmrc-ask-for-in-an-rd-enquiry/): the evidence a compliance check requests
- [Can HMRC make me pay back a credit?](https://www.limestonegrey.com/rd-tax-relief/questions/can-hmrc-make-me-pay-back-an-rd-tax-credit/): withholding, clawback, interest and the penalty bands
- [Which software and cloud costs qualify?](https://www.limestonegrey.com/rd-tax-relief/questions/which-software-and-cloud-costs-qualify/): the statutory definitions, the QIA carve-out and apportionment
- [What records do I need?](https://www.limestonegrey.com/rd-tax-relief/questions/what-records-do-i-need-for-an-rd-claim/): no statutory format; estimates built on evidence and reason
- [What is a scientific or technological uncertainty?](https://www.limestonegrey.com/rd-tax-relief/questions/what-is-a-scientific-or-technological-uncertainty/): the Guidelines definition, system uncertainty and the caveats
- [What doesn't count as R&D?](https://www.limestonegrey.com/rd-tax-relief/questions/what-doesnt-count-as-rd/): routine work, commercial novelty, project boundaries — and mathematics in scope since April 2023
- [How long does an HMRC enquiry take?](https://www.limestonegrey.com/rd-tax-relief/questions/how-long-does-an-hmrc-enquiry-take/): no statutory end date; the stages, closure notices, ADR, review and tribunal
- [Is there a maximum R&D claim?](https://www.limestonegrey.com/rd-tax-relief/questions/is-there-a-maximum-rd-claim/): no ceiling on qualifying spend; the PAYE cap and the old SME scheme's €7.5m project cap
- [How do I calculate staff costs?](https://www.limestonegrey.com/rd-tax-relief/questions/how-do-i-calculate-staff-costs-for-an-rd-claim/): earnings, employer NIC and pension apportioned to R&D time; dividends excluded
- [How long until an R&D tax credit is paid?](https://www.limestonegrey.com/rd-tax-relief/questions/how-long-does-it-take-to-receive-rd-tax-credit/): HMRC's published 40-day aim, what must be in place first, and what slows payment
- [How do I claim R&D tax credits?](https://www.limestonegrey.com/rd-tax-relief/questions/how-do-i-claim-rd-tax-credits/): the four steps — notification check, analysis, Additional Information Form, CT600 — and what HMRC does after filing
- [What qualifies for R&D tax credits?](https://www.limestonegrey.com/rd-tax-relief/questions/what-qualifies-for-rd-tax-credits/): the activity test and the cost categories in one answer, and why new to your company is not enough
- [Is R&D tax relief State aid?](https://www.limestonegrey.com/rd-tax-relief/questions/is-rd-tax-relief-state-aid/): the old SME scheme was, the current schemes carry no notified State aid machinery, and grants no longer restrict claims
- [Who can claim R&D tax relief?](https://www.limestonegrey.com/rd-tax-relief/questions/who-can-claim-rd-tax-relief/): companies within the charge to UK corporation tax, the trade condition, going concern and the excluded bodies
- [Can a partnership or LLP claim R&D tax credits?](https://www.limestonegrey.com/rd-tax-relief/questions/can-a-partnership-or-llp-claim-rd-tax-credits/): relief can reach a corporate member as reduced profits, but no payable credit
- [What are qualifying indirect activities?](https://www.limestonegrey.com/rd-tax-relief/questions/what-are-qualifying-indirect-activities/): the paragraph 31 list of supporting work that counts as R&D, and the staff costs it adds
- [What happens if my R&D claim is rejected?](https://www.limestonegrey.com/rd-tax-relief/questions/what-happens-if-my-rd-claim-is-rejected/): rejection, adjustment and enquiry are different things — the appeal chain, the review, and the window to claim again
- [How long does an R&D claim take to prepare?](https://www.limestonegrey.com/rd-tax-relief/questions/how-long-does-an-rd-claim-take-to-prepare/): what actually drives the elapsed time, and the two deadlines that decide whether a claim is possible at all
- [Do I need a technical report for an R&D claim?](https://www.limestonegrey.com/rd-tax-relief/questions/do-i-need-a-technical-report-for-an-rd-claim/): the Additional Information Form is mandatory; the fuller report is optional and when it earns its keep
- [Can I claim Patent Box and R&D tax relief together?](https://www.limestonegrey.com/rd-tax-relief/questions/can-i-claim-patent-box-and-rd-tax-relief-together/): yes — the 10% IP rate, the R&D fraction that ties it to your own R&D, and the election
- [What are R&D allowances?](https://www.limestonegrey.com/rd-tax-relief/questions/what-are-rd-allowances/): the 100% capital allowance for R&D capital spend — the counterpart to costs the credit cannot reach
- [Can a charity claim R&D tax relief?](https://www.limestonegrey.com/rd-tax-relief/questions/can-a-charity-claim-rd-tax-relief/): no, but its trading subsidiary may, and a contractor doing R&D for a charity can claim in its own right

## Sectors
- [Sector guides](https://www.limestonegrey.com/sectors/): R&D tax relief for the sectors whose business is their R&D
- [Life sciences](https://www.limestonegrey.com/sectors/life-sciences/): grant stacks, CRO and CDMO contracts, clinical trials and long pre-revenue phases
- [Biotech](https://www.limestonegrey.com/sectors/biotech/): why ERIS is the biotech scheme — the intensity test, the SME test for venture-backed groups, and the PAYE cap
- [Medtech](https://www.limestonegrey.com/sectors/medtech/): device development from prototype to clinical evaluation, and where routine regulatory work stops qualifying
- [Software](https://www.limestonegrey.com/sectors/software/): where software claims stand up and where they fail — advancing the technology, not the product
- [AI and robotics](https://www.limestonegrey.com/sectors/ai-and-robotics/): model, perception and control work that advances the field, under HMRC's closest scrutiny
- [Agritech](https://www.limestonegrey.com/sectors/agritech/): crop science, precision farming, controlled environment growing and livestock technology
- [Engineering](https://www.limestonegrey.com/sectors/engineering/): development beyond established practice, and who claims on contracted work
- [Manufacturing](https://www.limestonegrey.com/sectors/manufacturing/): product and process development, including the process side that is regularly missed
- [Construction](https://www.limestonegrey.com/sectors/construction/): the competent professional test applied honestly, and who owns the claim in a layered contract chain
- [Cleantech and energy](https://www.limestonegrey.com/sectors/cleantech-and-energy/): storage, hydrogen, grid and marine technology, with grant funding handled under the current rules
- [Semiconductors and photonics](https://www.limestonegrey.com/sectors/semiconductors-and-photonics/): device, process and packaging development, on the doorstep of the South Wales cluster
- [Aerospace and defence](https://www.limestonegrey.com/sectors/aerospace-and-defence/): certification-driven development, contracted programmes and who owns the claim
- [Space](https://www.limestonegrey.com/sectors/space/): satellite platforms, propulsion, ground segment and in-orbit technology

## Case studies
- [Case studies](https://www.limestonegrey.com/case-studies/): how claims are prepared and defended, in our clients' own words
- [Midtec Products](https://www.limestonegrey.com/case-studies/midtec/): a change in DEFRA emissions rules, a retrofit stove device, and a £40,000 R&D tax credit claim

## Location
- [R&D tax advice from Cardiff, for Wales and beyond](https://www.limestonegrey.com/rd-tax-advice-cardiff-wales/): the Cardiff-based firm, Welsh claim statistics from HMRC's regional table, and how engagements run UK-wide

## About
- [LimestoneGrey](https://www.limestonegrey.com/): a firm of chartered tax advisers and chartered accountants specialising in R&D tax relief; a member firm of CIOT and ICAEW
- [About the firm](https://www.limestonegrey.com/about/): who prepares the claims, and how the practice is built
- [The firm and its regulation](https://www.limestonegrey.com/regulation-and-standards/): CIOT and ICAEW member firm; how our guidance is written and reviewed
- [Matthew Jones ACA CTA](https://www.limestonegrey.com/about/matthew-jones/)
- [How we use AI](https://www.limestonegrey.com/ai-policy/)

## Working with us
- [What we do and how we work](https://www.limestonegrey.com/rd-tax-advisers/): the engagement end to end, who signs the claim off, fees aligned to outcomes, and when we say do not claim
- [How we work](https://www.limestonegrey.com/how-we-work/): scoping call to submission, fees agreed up front, HMRC enquiry support included as standard
- [A free second opinion on your claim](https://www.limestonegrey.com/claim-review/): a confidential review of a claim prepared elsewhere — a paid claim is not an approved claim
- [For accountants](https://www.limestonegrey.com/accountants/): referral or white-label R&D support, PCRT aligned, client relationship protected
- [Client testimonials](https://www.limestonegrey.com/testimonials/): reproduced word for word as clients gave them
- [Contact](https://www.limestonegrey.com/contact/): Cardiff office, 0330 223 4 223