Mandatory registration of tax advisers with HMRC

Overview of the new registration requirement

HMRC is introducing a mandatory registration system for all tax advisers who interact with HMRC on behalf of clients. From 18 May 2026, advisers must register via a new online system connected to HMRC’s Agent Services Account (ASA).

The aim of the legislation is to raise standards in the tax advice market. This article summarises the latest guidance and highlights practical steps for affected people.

Who must register?

HMRC defines a “tax adviser” very broadly and anyone who is interacting with HMRC regarding someone else’s tax affairs and receives payment for doing so is likely to be caught.

Interactions include phone calls, email, post, online messages via GOV.UK or the HMRC app, or submitting any return, claim, or document.

HMRC guidance confirms the obligation to register rests with the legal entity (unless a sole trade), rather than individual employees. Some individuals will need to be identified as “relevant individuals”, however; see further details below.

Who does not need to register?

HMRC’s guidance confirms that you do not need to register if you:

• Only handle tax matters for your own organisation (in house teams)
• Provide tax services for free
• Are legally required to interact with HMRC (e.g. insolvency practitioners)
• Provide software but do not interact with HMRC
• Only deal with customs or import VAT matters

It is not clear from the current guidance if exemptions will apply in certain situations including corporate groups where, for example, one entity deals with HMRC on behalf of other group companies.

Registration timeline

The registration timetable is phased as follows:

• 18 May 2026 – Registration opens. Initial registration is required for those who do not have either an ASA or a self-assessment or CT online account.
• 18 August 2026 – Existing agents with SA or CT accounts (but no ASA) must register.
• 18 November 2026 – Agents providing only third party payroll services must register.

The government has also recently confirmed that the registration of businesses in the financial services sector will be deferred until 31 March 2027.

Agents who already hold an ASA do not need to re register, but HMRC will contact them for additional information to verify compliance.

HMRC will allow a three month window from the date an adviser becomes required to register, during which businesses may continue interacting with HMRC; for example, those in the first wave will need to register by 18 August 2026. Other businesses that have a later registration deadline can choose to register early if they so wish.

Registration requirements

As mentioned above, the obligation to register will lie with the legal entity, unless a sole trader, (as the “tax adviser”) and not the individuals providing tax advice, however, information will need to be provided for certain “relevant individuals” as part of the registration application.

A relevant individual includes an individual who plays a significant role in:

• Making decisions about how the whole or a substantial part of the tax adviser activities of the organisation are to be managed or organised; or
• the actual managing or organising of the whole or substantial part of those activities.

The number of relevant individuals to be included on the registration application depends on the size of the business, albeit there is no cap on the maximum number of relevant individuals for larger businesses, as follows:

• Businesses with five or fewer officers – all officers must be listed on the registration, along with any employee meeting the “relevant individual” test.
• Businesses with six or more officers – any officers and employees who meet the definition of relevant individual above but, if this results in fewer than five officers, further officers must be added until at least five are listed.

This remains a contentious area, with professional bodies noting ambiguities in HMRC’s descriptions.

Conditions for registration

To be able to register, the business and each of the relevant individuals must not have any outstanding tax liabilities or returns, not be subject to an anti-avoidance measure, not be under HMRC sanctions or suspensions, nor have any criminal convictions. The business must also provide evidence that they are supervised for anti-money laundering and the individuals must not be disqualified from acting as a director, in the UK or overseas.

Penalties for non-compliance

There are both financial and operational penalties for non-compliance which could severely impact a business that does not meet the registration conditions or does comply including:

• Immediate suspension from interacting with HMRC.
• Financial penalties starting at £5,000 (which can be levied on both the business and the relevant individuals).
• Requirement for sanctioned advisers to inform their clients.

Key issues and unresolved points

Some additional guidance was published by HMRC in February, but it still leaves a number of uncertainties and unanswered questions including:

• It appears that all “tax advisers” as defined by HMRC will be required to apply for an ASA, even if they act as an agent for a HMRC service that does not currently require one (e.g. SDLT returns).
• The ICAEW notes that HMRC’s guidance is unclear on how to determine whether a person counts as an “officer” or relevant individual for registration purposes.
• It remains uncertain whether registration applies at entity or group level and whether family offices are required to register.

Practical steps for legal firms

To prepare for the new regime, businesses should:

1. Assess whether the businesses interacts with HMRC on behalf of clients in any capacity.
2. Confirm whether the business already has an Agent Services Account – only one ASA can be set up per business. If the business does have an ASA already, ensure contact details are up to date ahead of HMRC’s requests for verification.
3. Identify relevant individuals – Begin reviewing officer roles, governance structures, and employee responsibilities to determine relevant individuals.
4. Review registration conditions – Confirm that the business and relevant individuals are not likely to have any barriers with regards to meeting the registration conditions
5. Establish record keeping processes – As annual confirmation is expected, the registration conditions will need to be monitored, along with any changes in relevant individuals.

Conclusion

A number of businesses (beyond traditional accountants and tax advisers) are likely to be brought into scope of the new rules, given the broad application for the interaction with HMRC. With several areas still awaiting clarity, it is hoped that HMRC will issue further guidance in advance of the registration window opening on 18 May 2026, along with further information on the registration process.