Mandatory ‘tax adviser’ registration: impact on law firms

Within the recently enacted Finance Act 2026 are new legal requirements for ‘tax advisers’, who interact with HMRC on behalf of clients, to be registered with HMRC and meet certain ‘minimum standards’.

The scope of the new legislation is broad, and many law firms may find themselves subject to the registration requirements, even where tax work is only a small element of their overall business. There are various provisions which can impose financial and non-financial penalties on firms which fail to comply, so you should review your requirements now. Mandatory registration takes effect from 18 May 2026, with the first tranche of affected advisers needing to register within three months.

What the legislation means for law firms

The legislation operates to prohibit unregistered ‘tax advisers’ from interacting with HMRC in relation to clients’ tax affairs. In this context, ‘interaction’ involves any form of communication with HMRC or the filing of any returns, claims, or other documents.

As a result, firms will need to consider whether they meet the stipulated definition of ‘tax adviser’. The term is broad and comprises “an organisation that, in the course of a business carried on by it, assists other persons with their tax affairs”. This can in turn encompass any advice in relation to tax, acting as an agent in relation to tax, or the provision of any document that is likely to be relied upon by HMRC to determine a person’s tax position.

In the context of the legal sector, conveyancers submitting stamp duty land tax returns, corporate lawyers submitting stamp duty forms, private client lawyers submitting inheritance tax forms, or family lawyers communicating with HMRC will be treated as ‘tax advisers’ and, because they interact with HMRC, will need to be registered. There are, of course, multiple other situations where documents may be provided in relation to tax and registration therefore mandated if a firm is interacting with HMRC.

There are certain exceptions in the legislation which appear unlikely to apply to many law firms, but specific advice may be required.

Requirements and conditions

A firm within scope of the legislation should be considering an application for registration. As part of the application, the firm will need to provide:

• Their name and address.
• Confirmation that the organisation is registered with a supervisory authority (e.g. the Solicitors Regulation Authority) for anti-money laundering purposes.
• The names of ‘relevant individuals’. In the legislation the term ‘relevant individual’ encompasses anyone making decisions about how a substantial part of the organisation’s ‘tax adviser activities’ are to be managed or organised, or who otherwise actually manages or organises a substantial part of those activities. This is again a broad definition, and we are awaiting more detailed guidance from HMRC to enable firms to identify their ‘relevant individuals’ accurately.
• A statement confirming that the ‘registration conditions’ are met. The registration conditions, broadly, require the organisation and all relevant individuals to not have returns outstanding, outstanding tax liabilities, be subject to anti-avoidance measures, or be subject to certain other reprimands for various tax offences, insolvency, or disqualifications.

Firms should note that registration is at legal entity level, even where tax work is a small element of the overall services provided. Firms with more than one group entity carrying on tax services should make sure that they have considered which entities will need to be registered.

Timing of registration

The new requirements will apply from different points depending on which, if any, HMRC agent accounts an adviser already holds. Based on current HMRC guidance the relevant dates are as follows:

• No agent accounts: registration required within three months from 18 May 2026.
• No Agent Services Account (ASA), but an existing Self Assessment (SA) or Corporation Tax (CT) agent account: registration required within three months from 18 August 2026.
• No ASA or SA/CT agent accounts but the adviser provides third-party payroll services: registration required within three months from 18 November 2026.

Registration will be linked to a firm’s ASA, and advisers who already have an ASA will be required to provide additional information to bring their existing account in line with the new registration requirements rather than re-register. The timing for this is not certain but will presumably be after the various registration periods set out above.

Those responsible for registration at a firm may not have a clear view of which, if any, agent accounts are in use. It will be important that firms establish this as soon as possible so that they are clear on the relevant deadline.

Consequences of non-compliance

HMRC have the power to suspend a firm’s registration for a breach of the registration conditions described above or where the tax advisers conduct has fallen below the ‘minimum standards’ (currently expected to align with HMRC’s published Standard for Agents). As this would have a significant impact on a firm’s ability to carry out tax work, we hope both that HMRC will look to work with firms to identify and correct minor breaches and that the detailed guidance on the new requirements will set out a clear process for this.

Financial penalties can apply where a firm attempts to interact with HMRC without being registered, or while its registration is suspended.

Given the proximity of these changes and both the financial and non-financial implications for non-compliance, you should review your firm’s position imminently.

To date, the HMRC guidance is limited but more detail is expected ahead of 18 May. Affected firms should keep abreast of the guidance to ensure that they are prepared for registration. If you’d like more information or support, please get in touch with our law firms specialists.