The wheels of the civil service can turn slowly.  But when it comes to mandatory tax adviser registration, the government is leaving it a little close for comfort.  In theory the system for registration with HMRC is opening from May 2026, with a transitional period of at least 3 months.  But as yet there is precious little guidance on the scope of some of the legislative obligations which will soon apply to a variety of law firms, accountancy practices, and other professional service providers, from the mightiest global behemoth to a one-person high street practice.

The new rules are being introduced in the Finance Bill currently going through Parliament. Under those rules (as currently drafted – see links below) most professional service providers will be subject to mandatory registration if they want their organisation to be able to 'interact' with HMRC on behalf of clients (in summary, this includes making filings and otherwise communicating with HMRC in relation to the tax affairs of clients).  Current registration systems are patchy and there is no overarching framework.  The thinking behind this new system is (at least partly) that it will allow HMRC to track, and if necessary sanction, rogue operators.

There are lots of areas that would benefit from detailed operational guidance from HMRC (including the scope of some of the limited exemptions) but one of the biggest areas of concern is the scope of the concept of 'relevant individual'. 

It will be the service provider organisation that will be required to register with HMRC as a tax adviser.  However, as part of the registration process, the organisation will have to identify and name all individuals (referred to in the legislation as 'relevant individuals') who play a significant role in:

• the actual management and organisation of the whole or a substantial part of the 'tax adviser activities' which the firm carries on; or
• (one step removed) the making of decisions about such management / organisation.

Tax adviser activities are themselves widely defined and go substantially beyond the plain English meaning of the phrase. For example, it includes providing assistance with any document that is likely to be relied on by HMRC in determining a client's tax position which, in the absence of additional detail or guidance, is clearly a potentially very broad category that could pull in a wide array of documentation. 

Organisations don't just have to notify HMRC of the individuals they consider to be 'relevant individuals'.  The organisation must also give a statement to HMRC that all of those relevant individuals meet a number of conditions, including that they are up to date with their personal tax obligations, not subject to various anti-avoidance measures, haven't been subject to anti-avoidance penalties and don't have certain unspent convictions (primarily for dishonesty offences).

You can start to see that it becomes incredibly important to identify the relevant individuals in your organisation. There is no upper limit in the legislation on the number of relevant individuals who must be identified and, in the absence of guidance, it's currently unclear exactly what HMRC might consider is entailed by 'playing a significant role' in managing / organising tax adviser activities. Note that whilst a 'relevant individual' isn't necessarily an 'officer' of the organisation, there is a minimum number of officers who must be identified: (i) if the organisation has five or fewer officers, all officers must be named; or (ii) if the organisation has six or more officers but fewer than five officers are identified under the managing / organising criteria (see above), additional officers must be named to ensure that at least five officers are identified as relevant individuals. For these purposes, 'officers' include company directors, LLP members, partners in partnerships, etc.

Any organisation that has any interaction with HMRC as part of their professional services will need to lay some of the groundwork in analysing their business to work out key areas of tax adviser services and related management / organisation decision making.  For many there will be a list of individuals who clearly and obviously fall in the relevant individual category and then an ever-widening halo of people who might be included.  For example: in a law firm, is the head of the real estate team (who in turn manages the juniors / paralegals who generate stamp duty land tax returns) a 'relevant individual'?  Does it depend on the volume of real estate business being undertaken in absolute terms? Relative to the firm?  Relative to the tax services provided? These sorts of questions will need to be carefully considered with reference to the organisation's decision making structure and, ultimately, the much anticipated HMRC guidance.

The best preparation at this stage for most organisations will be to commence the above analysis and to draw up longlists and shortlists (and maybe mediumlists!) of relevant individuals.  Firms might even start contacting those individuals (particularly where any delay is anticipated or there is a significant number of potential relevant individuals) to warn them that they may need to provide information about their personal tax affairs and other confirmations.  HMRC has a lot of the cards here; being prohibited from communicating directly with HMRC would be incredibly disruptive for many of the businesses caught within the scope of the registration requirements.  Having a strategy for registration – and maintaining that registration – therefore becomes a business critical and reputational issue.

Helpful links:

Current Draft Finance Bill: https://publications.parliament.uk/pa/bills/cbill/59-01/0377/240377.pdf

HMRC Policy Paper, November 2025: https://www.gov.uk/government/publications/mandatory-tax-adviser-registration-with-hmrc/tax-advisers-to-register-with-hmrc-and-meet-minimum-standards