LimestoneGrey is a member firm of both the Chartered Institute of Taxation (CIOT) and the Institute of Chartered Accountants in England and Wales (ICAEW): a firm of chartered tax advisers that is also a firm of chartered accountants. We are regulated by ICAEW, bound by Professional Conduct in Relation to Taxation (PCRT), supervised by ICAEW for anti-money laundering, and registered with HMRC as a tax adviser. Much of the damage done in the R&D mis-selling era was done by firms subject to none of these. This page explains what each layer means for you as a client.
What does being a CIOT member firm mean?
The Chartered Institute of Taxation is the leading professional body in the UK for tax advisers, and the CTA qualification it awards is the benchmark for UK tax practice. As a CIOT member firm, our tax advice is given under the Institute’s professional rules and PCRT. That matters here because R&D tax relief is tax law before it is anything else: the definition of qualifying R&D, the cost categories, the procedural requirements and the enquiry process all come from statute and guidance, and we read them as chartered tax advisers first.
What does ICAEW regulation mean for you?
It means the firm answers to a professional body, not just to its own marketing. As an ICAEW-regulated firm we are subject to the Institute’s professional standards and disciplinary framework, our anti-money-laundering compliance is supervised by ICAEW, and there is an independent route for complaints if we ever fall short. Our founder, Matthew Jones ACA CTA, is a member of both institutes and bound by their codes of conduct; every claim the firm submits is signed off by a chartered adviser.
What is PCRT and why does it matter in R&D claims?
PCRT is the professional code that governs tax advice given by members of the main UK accountancy and tax bodies. For R&D work its practical effect is simple: we may only advise a filing position that has a sustainable basis in law, we must not let a fee incentive shape a technical judgement, and we must correct errors when we find them. An agent outside PCRT can file whatever it thinks HMRC will not notice. We cannot, and would not want to. We set out what these standards mean in day-to-day R&D work in professional standards in R&D tax advice.
Is LimestoneGrey registered with HMRC?
Yes. Under the Finance Act 2026, tax advisers who interact with HMRC on behalf of clients must be registered with HMRC, with anti-money-laundering supervision a condition of registration. The requirement takes effect in stages from 18 August 2026. We meet both requirements through our ICAEW regulation. When we file your Additional Information Form and deal with HMRC on your claim, we do so as a registered, supervised adviser named on the submission.
Why are unregulated R&D agents a risk?
Because when a claim goes wrong, the company is the one that repays. HMRC can reach a bad adviser too, but every route to them turns on intent, and none of them reaches one who was simply too optimistic and has since stopped trading. Your directors are responsible for the accuracy of the return, HMRC checked around one in six R&D claims in 2023-24 on its latest published figures, and an unregulated agent has no professional body to answer to, no PCRT duties and no complaints route. HMRC’s own estimates show why scrutiny tightened: error and fraud in R&D relief ran at 17.6% in 2021-22 before falling to a measured 6.4% in 2023-24, with HMRC estimating 5.3% for the two years since, as compliance activity increased. If your current adviser will not defend its work in an HMRC enquiry, that tells you what it thinks of its own claims. LimestoneGrey has been regulated since its inception in 2017: the standards this page describes are not ones we adopted when scrutiny arrived.
How our guidance is written and reviewed
The same standards apply to what we publish as to what we file. Every guide and article on this site names its author and the month it was last reviewed, and that date means the page was actually re-checked against the current legislation and guidance, not simply re-stamped. Our technical content is written and reviewed by the chartered advisers who prepare claims, under the same PCRT duties that govern our advice: statements of law are cited to their primary sources, gov.uk guidance and HMRC’s CIRD manual, so you can verify them rather than take our word.
Rates, thresholds and deadlines are re-verified when the rules change and ahead of each April rule cycle. If we find an error in something we have published, we correct the page and update its review date; we would rather show a correction than defend a mistake. Where we use AI in preparing content, a chartered adviser reviews the output before it is published, as set out in how we use AI. And we publish no statistic about our own performance that we cannot reconcile to our records, which is why you will not find a “success rate” on this site: no honest adviser controls HMRC’s decisions, and no unverifiable number belongs on the website of a regulated firm.
One distinction matters alongside all of this: our guides are carefully prepared general information, not advice on your circumstances, as our terms explain. Advice comes through an engagement, where it carries the professional protections described on this page.
What happens if you have a complaint?
Raise it with Matthew directly and we will deal with it quickly and openly. If you are not satisfied with our response, you can escalate the matter to ICAEW, which independently handles complaints about the firms it regulates. Few R&D agents can offer that second step; we regard it as basic client protection.
Our commitments to every client
- The right claim, defensibly prepared: we file nothing we cannot stand behind.
- Every claim is prepared or reviewed by a chartered adviser before it is submitted.
- The fee is agreed before work starts, with no hidden costs.
- Enquiry support is included as standard.
- Where the law is unsettled, we tell you so and explain the position we take.
- We are open about our methods, including how we use AI in our work.
If these standards match what you are looking for in an adviser, start a conversation with us or read how we work.
Written by Matthew Jones ACA CTA. Last reviewed August 2026.
