LimestoneGrey is a firm of chartered tax advisers and chartered accountants specialising in R&D tax relief. It is the only thing the firm does, and it has been since Matthew Jones ACA CTA founded it in 2017 — before the current schemes existed, through the reforms that replaced them and through the compliance drive that followed. This page sets out what an engagement actually involves.
If you are still deciding who to appoint rather than what to ask us, start with how to choose an R&D tax adviser. It sets out what can be verified about anyone you are considering, including us.
What the engagement covers
An R&D claim is two jobs bolted together, and we do both.
The first is the technical case. Someone has to sit with the people who did the work, follow what they were trying to achieve and frame it against a statutory test that asks about advances in science or technology and uncertainties a competent professional could not readily resolve. That is an interviewing and writing job, and it is done by someone who can hold the conversation with your engineers without either side losing patience.
The second is the tax. Which scheme the period falls under, what qualifies as a cost and in what proportion, how the credit runs through the corporation tax computation, whether the PAYE cap bites, and whether a claim notification was needed and filed in time. Get that wrong and the technical case never gets read, because the claim is invalid before anyone reaches it.
We prepare the computations, the report and the Additional Information Form, and we file as registered tax agents rather than handing you a pack and leaving the submission to someone else. How we work walks through the sequence from scoping call to submission.
Who does the work
Your first conversation is with a qualified adviser rather than a salesperson, and it is the same team that goes on to prepare the claim. There is no delivery department the file gets passed down to once the engagement is signed.
Every claim the firm submits is signed off by a chartered adviser before it reaches HMRC. That is the part worth pinning down with any firm you speak to, because it is where responsibility actually sits.
We file as registered tax agents without taking a 64-8, so if you have an accountant, their authorisation for your wider tax affairs is untouched and their relationship with you is unchanged. Many accountants send this work to us for that reason; working with accountants covers how that arrangement runs.
Fees, and what happens when HMRC asks
Our fees are aligned to outcomes and agreed before any work starts. There are no hidden costs, and we set out the exact fee for your situation at the end of the scoping call, so you decide with the number in front of you.
Because the fee is tied to the outcome, the incentive question is a fair one to put to us, and the answer is that we will tell you on the first call if we do not think you should claim. That is a cheaper conversation for both of us than an enquiry two years later.
Enquiry support is included as standard in every engagement, written into the engagement letter rather than offered as goodwill. HMRC checked around one in six R&D claims in 2023-24, the most recent year it has published, so this is not a remote contingency. HMRC enquiries sets out what the support involves.
What being regulated means here
LimestoneGrey is a member firm of both the Chartered Institute of Taxation and ICAEW, regulated by ICAEW, bound by the Professional Conduct in Relation to Taxation code, supervised by ICAEW for anti-money laundering and registered with HMRC as a tax adviser. Regulation and professional standards explains what each layer means, including the independent complaints route to ICAEW if we fall short.
Two of those are legal requirements rather than credentials, and it is worth knowing which. Anti-money-laundering supervision is compulsory for any firm advising on tax affairs, and trading without it is a criminal offence. Under Part 7 of the Finance Act 2026, anyone paid to deal with HMRC on a client’s behalf must also be registered with HMRC as a tax adviser, a registration HMRC can refuse, suspend or withdraw. That requirement takes effect in stages, starting on 18 August 2026 — does my R&D adviser have to be registered with HMRC? covers the dates and what you can and cannot check.
Neither of those puts a qualification behind the advice. “Tax adviser” remains an unprotected title: no exam is required to use it, and there is no public register a prospective client can search. The checkable things are the professional bodies’ own registers, and those only help where the adviser is actually a member of one.
Whether we are the right fit
Probably yes if your R&D is genuinely technical, if you want the person who understands the claim to be the person who defends it, and if you would rather be told early that something does not qualify than find out during an enquiry.
Probably not if what you want is the largest number anyone will put on a form. That market exists. We are not in it.
The sectors we work in are a better guide to technical fit than geography. Most of the work runs on video calls and shared documents, which has been true for clients ten minutes from the office and three hundred miles away alike. If you are in Wales, R&D tax advice from Cardiff covers what being a Welsh firm does and does not mean.
If you already claim and want a second opinion rather than a new adviser, our free claim review is a confidential read on a claim that has already been filed. A paid claim is not an approved claim.
How to start
A scoping call, half an hour or so. You describe what the company builds and where the technical difficulty sat; we give an honest view on whether it looks like qualifying R&D, which scheme applies and what a claim would involve. It costs nothing and commits you to nothing.
Call 0330 223 4 223 or send us a message.
Sources
- Finance Act 2026, section 223 — the requirement for a tax adviser to be registered with HMRC before interacting with HMRC on a client’s behalf.
- The Finance Act 2026 (Registration of Tax Advisers) (Appointed Days and Transitional Provision) Regulations 2026, SI 2026/807 — regulation 4, the appointed days on which the registration requirement takes effect for each tranche, starting 18 August 2026.
- Check if and when you need to register as a tax adviser with HMRC — HMRC’s guidance, giving the date each registration window opens.
- Anti-money laundering registration — supervision as a legal requirement: “You’re breaking the law if you carry on a business activity covered by the regulations but do not register with a supervisory authority.”
- The Money Laundering Regulations 2017, regulation 86 — trading without required registration as a criminal offence.
- HMRC’s approach to R&D tax reliefs 2023 to 2024 — compliance coverage of 17% of claims in 2023-24, the most recent year published.
Written by Matthew Jones ACA CTA. Last reviewed August 2026.
