United Kingdom: Professional body rules | Research Credit Integrity Alliance

This page sets out what the codes of the main United Kingdom accounting and tax professional bodies say about fees, and in particular about contingent fees, for tax work such as research and development (R&D) relief claims. It describes the rules only and makes no recommendation.

Who these rules apply to

Professional body rules bind members of the body that issues them. They do not bind advisers who are not members. HMRC estimates that around 65 percent of agents are members of professional bodies.1 HMRC's 2024 consultation on the tax advice market noted that, compared with practitioners outside a professional body, members generally must hold a relevant qualification, hold professional indemnity insurance, undertake continuing professional development and follow their body's code of conduct.2

This page covers three sets of rules:

Rules	Issued by	Covers
Professional Conduct in Relation to Taxation (PCRT), effective 1 January 2026	AAT, ACCA, ATT, CIOT, ICAEW, ICAS and STEP jointly3	Members of those seven bodies who practise in tax3
Professional Rules and Practice Guidelines (PRPG), effective 9 November 2018, updated 1 January 2021	Chartered Institute of Taxation (CIOT) and Association of Taxation Technicians (ATT)4	CIOT and ATT members4
ICAEW Code of Ethics 2026, applying from 1 July 2026	Institute of Chartered Accountants in England and Wales (ICAEW)5	ICAEW members, including affiliates and employees of member firms, and member firms where relevant5

The separate codes of ACCA, ICAS, AAT and STEP were not reviewed for this page.

Professional Conduct in Relation to Taxation

PCRT consists of five Fundamental Principles for the provision of tax services and five Standards for Tax Planning.3 Members have a responsibility to adhere to PCRT, and a member who fails to do so is liable to be subject to disciplinary process.3 HMRC acknowledges that PCRT is an acceptable basis for dealings between members and HMRC, and HMRC's own standard for agents states that HMRC recognizes and endorses PCRT.31

The principles most relevant to fees are these:

Integrity. A member must act straightforwardly and honestly in all dealings with clients and tax authorities, and do nothing knowingly or carelessly that might mislead.3
Objectivity. Relationships where there are conflicts of interest or which bias or unduly influence the member's professional judgment must be avoided.3
Commission. A member must always disclose to the client if it receives commission, incentives or any other advantage from a third party relating to the matter on which it is advising, and the amounts or the basis on which they are calculated.3
Competence. A member must not undertake professional work which it is not competent to perform unless it obtains appropriate assistance from a suitably qualified specialist.3

The PCRT text effective 1 January 2026 does not contain a provision dealing specifically with contingent fees.3 Fee rules are set by each body's own code, two of which are summarized below.

CIOT and ATT: Professional Rules and Practice Guidelines

The PRPG say that a member should ensure the client clearly understands the basis on which fees will be charged, and that it will usually be appropriate to set this out in the letter of engagement.4 Fee arrangements are a matter to be agreed between member and client, and the fee may have regard to the responsibility, nature and importance of the work, the time devoted to it and the benefit to the client.4 The possible arrangements listed are:

Arrangement	What the PRPG say
Time and expenses	Charged on time spent according to the skill and resources deployed4
Fixed fees	Based on a clear scope of work and proper costing of the work within the fee4
Contingent (including success) fees	Covered in a separate section on contingent fees4
Insurance	Fees covered in whole or part by professional fee insurance, for example in the event of an HMRC enquiry4

On contingent fees, the PRPG state that:

contingent fees can carry increased risks, such as a third party questioning the independence and objectivity of a member, so where a contingent fee basis is adopted a member should take care to ensure that its conduct meets, and is seen to meet, the required principles of integrity and objectivity;
a member should be aware that there may be legal or regulatory restrictions on having a contingent fee;
it is advisable for the engagement letter to set out the scope of the work covered and the action to be taken if later events cancel all or part of the benefit to the client, including whether part or all of the fee is to be repaid and whether interest is payable;
a member is advised to consider whether the contingent basis should be disclosed in any document in the public domain, or disclosed to a third party who may rely on it; and
a member should be aware of the rules on disclosure of tax avoidance schemes, where a contingent fee may be considered a premium fee.4

Where a member receives commission from someone other than the client as a result of advice, the PRPG say the member should tell the client, and give the amount, no later than when the advice is given.4

ICAEW Code of Ethics

Section 330 of the ICAEW Code deals with fees and other types of remuneration. It requires a professional accountant to explain the basis on which fees will be calculated, to give an estimated initial fee where applicable at the earliest opportunity, and to provide fee quotes or the basis of fees in writing.5 An accountant must not mislead clients about the basis of fees, and must provide a fee breakdown if the client asks for one.5

On contingent fees, the Code says they are used for certain types of non-assurance services but might create threats to compliance with the fundamental principles, particularly a self-interest threat to objectivity.5 Factors relevant to evaluating the threat include the nature of the engagement, the range of possible fee amounts, the basis for determining the fee, disclosure of the basis of remuneration, and whether an independent third party is to review the outcome.5 Examples of possible safeguards are review of the work by someone not involved in it, and advance written agreement with the client on the basis of remuneration.5

For audit work the Code goes further. A firm shall not charge a contingent fee for an audit engagement, and in some circumstances shall not charge one for a non-assurance service, such as tax work, provided to an audit client.5

ICAEW's guidance on charging fees states that the amount of a fee is a commercial matter between the parties and, apart from insolvency engagements, is not addressed by professional regulation. It adds that a contingent basis may heighten, or be perceived to heighten, the economic incentive to advise in a certain manner, so that safeguards may be needed.6

How the rules connect to HMRC

HMRC's standard for agents says HMRC works with professional bodies to make sure there is a consistent approach to breaches of professional standards, and that relevant professional bodies will, where appropriate, be told directly about misconduct by their members.1 HMRC expects members to follow their body's code of ethics, and says that if they do, its own standard should not place further requirements on them.1 HMRC has also set up an R&D Professional Bodies mailbox, a dedicated route for professional bodies to contact HMRC about R&D or breaches in standards relating to R&D.7

Sources

HM Revenue and Customs, The HMRC standard for agents (updated 9 February 2026), sections 2, 2.1, 2.2 and 3.2. https://www.gov.uk/government/publications/hmrc-the-standard-for-agents/the-hmrc-standard-for-agents (accessed 11 October 2026). Back
HM Revenue and Customs, Raising standards in the tax advice market: strengthening the regulatory framework and improving registration (consultation, 6 March 2024), section "The current partial regulatory framework". https://www.gov.uk/government/consultations/raising-standards-in-the-tax-advice-market-strengthening-the-regulatory-framework-and-improving-registration/raising-standards-in-the-tax-advice-market-strengthening-the-regulatory-framework-and-improving-registration (accessed 11 October 2026). Back
AAT, ACCA, ATT, CIOT, ICAEW, ICAS and STEP, Professional Conduct in Relation to Taxation (effective 1 January 2026, published 1 October 2025), Foreword and paragraphs 1.2, 1.7, 1.10, 1.11, 2.2, 2.4, 2.5, 2.9 and 2.13. https://www.icaew.com/-/media/corporate/files/technical/tax/pcrt/pcrt-effective-1-january-2026.ashx (accessed 11 October 2026). Back
Chartered Institute of Taxation and Association of Taxation Technicians, Professional Rules and Practice Guidelines (effective 9 November 2018, updated 1 January 2021), paragraphs 8.1.1, 8.1.2, 8.2.1 to 8.2.5 and 8.3.1. https://www.att.org.uk/sites/default/files/PRPG%20%28Update%201.1.2021%29%20-%20Final.pdf (accessed 11 October 2026). Current edition confirmed on the CIOT page https://www.tax.org.uk/professional-rules-and-practice-guidelines (accessed 11 October 2026). Back
ICAEW, ICAEW Code of Ethics 2026 (applies from 1 July 2026), paragraph 1.1, section 330, paragraphs R330.4, R330.5, R330.7 and R330.4B.1 and the paragraphs headed "Contingent Fees", and section 410, paragraphs R410.9 and R410.10. https://www.icaew.com/-/media/corporate/files/technical/ethics/code-of-ethics/icaew-code-of-ethics-2026-revisions-highlighted.ashx (accessed 11 October 2026). Back
ICAEW, Determining the basis of charging fees (guidance issued March 2017, updated February 2020), paragraphs 2 and 7. https://www.icaew.com/-/media/corporate/files/technical/ethics/icaew-guidance-determining-the-basis-of-charging-fees-guidance.ashx (accessed 11 October 2026). Back
HM Revenue and Customs, Approach to Research and Development tax reliefs 2023 to 2024 (published 30 October 2024), section 2.2, Table 3, and section 2.5. https://www.gov.uk/government/publications/hmrcs-approach-to-research-and-development-tax-reliefs-2023-to-2024/approach-to-research-and-development-tax-reliefs-2023-to-2024 (accessed 11 October 2026). Back