United Kingdom: Overview

1. Ask whether the adviser is registered with HMRC, and which professional body, if any, each named person belongs to. Registration is now a legal requirement for advisers who deal with HMRC for clients;3Source 3HMRC manual MTAR10100 and MTAR10800 (8 October 2026): all tax advisers who interact with HMRC on behalf of clients must register unless an exception applies (Finance Act 2026 section 224); registration windows from 18 May 2026; HMRC policy paper, Tax advisers to register with HMRC and meet minimum standards (26 November 2025). membership of a professional body is voluntary and brings its own rules and complaints process. The checking an adviser's credentials page says how to check both and what a listing does and does not tell you.
2. Ask who will be named on the additional information form. The form takes the full name and business name of every agent involved in the claim;1Source 1HMRC, Submit detailed information before you claim Research and Development (R&D) tax relief (26 September 2025): contact details of "all agents involved in the R&D claim, including any agent who has given advice"; "If you do not submit this form, any R&D or expenditure credit claim will not be accepted"; HMRC manual CIRD182000 (25 August 2026): claims made on or after 8 August 2023. an adviser who expects not to appear on it should explain why. The who is named on the claim? page covers the question in general.
3. If this is a first claim, check the claim notification deadline. For accounting periods beginning on or after 1 April 2023, a company claiming for the first time, or whose last claim was more than three years before the end of the notification period, must send HMRC a claim notification form. The deadline is six months after the end of the period of account, and without the form the claim is invalid. The form asks for the contact details of all agents involved in the claim.4Source 4HMRC, Tell HMRC that you're planning to claim Research and Development (R&D) tax relief (published 1 April 2023, last updated 31 October 2024). An adviser who proposes a first claim without raising it is a reason to ask more questions.
4. Ask how the fee is calculated and what it covers. The engagement letter decides four things: what the fee is a percentage of, what happens to it if HMRC reduces the claim, whether help with a compliance check is included, and who owns the working papers. Read it against the twenty questions and the contracts section. The fee and preparer rules themselves are on the sister site linked beside this page.
5. Read the technical descriptions before the form goes in. The company signs the return and answers for it; the your responsibility page sets out what that means, including the two year time limit for making or amending a claim and HMRC's time limits for enquiries and discovery assessments.

If HMRC opens a compliance check, read if your claim is reviewed and take advice before you reply. If the problem is the adviser, the complaints about an adviser page sets out the order: the firm first, then its professional body, then HMRC, which can apply sanctions to advisers who do not meet its registration conditions.5Source 5HMRC manual MTAR30700 (8 October 2026): from 18 August 2026 sanctions may apply to tax advisers who fail to meet the registration conditions.

• Checking an adviser's credentials, your responsibility, if your claim is reviewed and complaints about an adviser
• Who is named on the claim? and what qualifications does the team have?
• How to choose an R&D tax adviser

Sources

1. HMRC, Submit detailed information before you claim Research and Development (R&D) tax relief (26 September 2025): contact details of "all agents involved in the R&D claim, including any agent who has given advice"; "If you do not submit this form, any R&D or expenditure credit claim will not be accepted"; HMRC manual CIRD182000 (25 August 2026): claims made on or after 8 August 2023.   Back
2. HMRC, HMRC: the standard for agents (9 February 2026).  Back
3. HMRC manual MTAR10100 and MTAR10800 (8 October 2026): all tax advisers who interact with HMRC on behalf of clients must register unless an exception applies (Finance Act 2026 section 224); registration windows from 18 May 2026; HMRC policy paper, Tax advisers to register with HMRC and meet minimum standards (26 November 2025).   Back
4. HMRC, Tell HMRC that you're planning to claim Research and Development (R&D) tax relief (published 1 April 2023, last updated 31 October 2024).  Back
5. HMRC manual MTAR30700 (8 October 2026): from 18 August 2026 sanctions may apply to tax advisers who fail to meet the registration conditions.  Back