Short answer
Two separate things now apply. First, HMRC has long expected every agent — professional body member or not — to meet a baseline, non-statutory Standard for Agents. Second, and new, a statutory registration regime is being phased in from 18 May 2026 to 31 March 2027: anyone acting professionally as a tax adviser, including on R&D claims, must register with HMRC and pass a fit-and-proper test, or HMRC can refuse to deal with them. Members of a recognised professional body — ICAEW, CIOT, ATT and similar — are additionally bound by that body’s own conduct code, which includes guidance written specifically for R&D tax relief work.
Applies to
- Schemes
- All periods
- Periods
- 18 May 2026 onwards
- Claimants
- All
The long-standing Standard for Agents
HMRC has operated a Standard for Agents for years, independent of the new registration regime described below. It sets minimum expectations for anyone representing or advising a taxpayer — most relevant to agents who aren’t members of a professional body, since professional body members are already bound by their own, more detailed code. Where an agent falls short, HMRC can respond directly, including declining to deal further with that agent. It’s periodically updated — most recently on points including agents never being permitted to ask a client to share their HMRC sign-in details, and the correct handling of income tax repayment assignments.
The new mandatory registration regime
Finance Act 2026 introduced a legal requirement, rolled out in phases between 18 May 2026 and 31 March 2027, that a tax adviser may not interact with HMRC on a client’s behalf at all unless registered — covering phone, post, email, web portal messages, filed documents, and any other form of contact. It applies whether the adviser or the client is based in the UK, and it applies to the adviser as a business, not just to the individual staff member who happens to make contact.
The rollout runs in four phases, broadly ordered by what kind of HMRC account the adviser already holds: new advisers with no existing account first (18 May – 18 August 2026), then advisers with an existing Self Assessment or Corporation Tax account (18 August – 18 November 2026), then payroll-only service providers (18 November 2026 – 18 February 2027), and finally advisers who already hold an Agent Services Account — the account needed to submit the additional information form on a client’s behalf — together with financial services organisations (31 December 2026 – 31 March 2027). Falling into the last phase is a later deadline to register by, not registration that’s already happened.
To register, a firm has to satisfy conditions covering three broad areas: no unresolved tax compliance problems of its own (outstanding returns or payments, refusal-to-deal history with HMRC, involvement in anti-avoidance arrangements, disqualified directors, or unspent convictions for relevant offences); registration with an anti-money-laundering supervisor, or being in the process of getting one; and naming the individuals who actually run the tax advisory side of the business. There’s no fee to register.
The consequences of not registering escalate. Unauthorised contact from an unregistered adviser triggers a compliance notice; further unauthorised contact brings escalating financial penalties for the firm and the individuals involved, up to a permanent bar from registering. A registered firm can still be suspended — for up to twelve months — if its conduct falls below what’s required.
Professional body membership and PCRT
Membership of a recognised professional body — ICAEW, CIOT, ATT, ACCA, ICAS and others — brings an adviser under Professional Conduct in Relation to Taxation (PCRT), a more detailed code than HMRC’s baseline standard. The PCRT bodies have issued dedicated guidance specifically on R&D tax relief work, aimed primarily at their own members but also usable by a client who wants to understand what should and shouldn’t be claimed on their behalf.
Registration and PCRT membership are two different things, and neither substitutes for the other. Registration is the new legal minimum everyone has to meet. PCRT is a professional body’s own, more detailed standard, and only binds an adviser who has chosen to belong to one of those bodies.
What this means in practice
Neither the registration regime nor PCRT membership makes a claim itself correct — responsibility for what’s in the return still sits with the company, whatever standards its adviser is held to. What they do give a client is a genuine, checkable floor: whether the adviser is required to be registered with HMRC by now, whether it’s under anti-money-laundering supervision, and whether it or its named staff belong to a body bound by PCRT are all facts a client can ask about and expect a straight answer to, independently of anything the adviser says about its own track record.
One thing worth knowing directly, rather than assuming: an adviser who already submits the additional information form digitally on a client’s behalf holds an Agent Services Account, which places them in the last of the four phases above — but that only affects the date by which they need to register, not whether they’ve already done so. It isn’t a substitute for asking the adviser directly about their current registration status, particularly while the rollout is still running.
Worked example
A company engaged a contingency-fee R&D specialist that isn’t a member of any professional body. By the time the firm’s registration phase falls due, it hasn’t registered with HMRC — and HMRC then declines to deal with the firm on the client’s ongoing enquiry, issuing a compliance notice for continuing to make contact regardless. That doesn’t excuse the company from its own claim: the return still stands or falls on its own merits, and the enquiry into it proceeds regardless of what happens to the adviser. But it does mean the company is suddenly without the adviser who prepared the claim it now has to defend, at exactly the point it needs them most — a risk that was checkable and avoidable before the engagement started.
Where claims go wrong
- Treating an adviser’s confidence, or a contingent fee structure, as evidence the technical position is sound. Neither is a substitute for checking registration status, professional body membership, or asking who specifically is standing behind the technical claims being made.
- Not checking registration and professional body status before engaging an adviser, then discovering only during an enquiry — or worse, when HMRC declines to deal with the adviser at all — that there’s no real accountability behind the firm.
- Assuming HMRC’s registration regime or an adviser’s professional body membership protects the company if the underlying claim is wrong. It doesn’t. The company’s own responsibility for its return is unaffected either way.
- Assuming professional body membership alone means PCRT’s specific R&D guidance was actually followed on this particular claim. Membership is a necessary check, not a sufficient one.
- Confusing an adviser’s own conduct obligations with the company’s own record-keeping duty. The two are separate, and the second doesn’t go away because the first is satisfied — see What records do I need to keep to support an R&D tax relief claim?
John Mapother
Founder & Director
Last reviewed 2 September 2026