Three months ago we wrote about the countdown to mandatory tax adviser registration and wondered what exactly we were counting down to.  On 18 May 2026 HMRC opened its online registration portal.  Tax advisers who do not already hold an Agent Services Account can begin registering.  This kind of account will be the vehicle through which the mandatory tax adviser registration is operated.

For those who have no existing agent account with HMRC, the clock is already ticking; they have until 18 August 2026 to register, to ensure that they will continue to be able to communicate with HMRC.

Those with a Self-Assessment or Corporation Tax account for agents (but not the more modern ‘Agent Services Account’) have an extra three months - until 18 November 2026 – before they need to register.

There are even later deadlines for pure payroll service providers and financial services providers.

For those with Agent Services Accounts, HMRC will contact them about fulfilling the requirements in order to stay registered.

On the conveyancing front, HMRC has been in discussions with the Law Society and real estate practitioners about how the new regime applies to firms whose only interaction with HMRC is submitting SDLT returns. Those discussions have reinforced the message: conveyancing firms are within scope. Filing an SDLT return on behalf of a client is sufficient, regardless of whether any tax advice is actually being provided.

Still Waiting: Guidance for Larger Organisations

For larger accountancy practices and multidisciplinary law firms – those with tax specialists who are unambiguously caught by the new rules – the more pressing concern is not whether to register but how to do so properly. The concept of a 'relevant individual' remains under-defined. Firms must identify individuals who play a significant role in the management or organisation of their tax adviser activities, or in decision-making about that management. In a large firm with multiple practice areas, drawing the boundary is genuinely difficult

We are still waiting – and hoping – for detailed HMRC guidance on how to identify relevant individuals in complex organisations and on what procedures firms should adopt to ensure ongoing compliance with the registration conditions (including monitoring the personal tax affairs of those individuals). Until that guidance materialises, firms will need to work from first principles: mapping their tax adviser activities, drawing up long-lists and short-lists of potential relevant individuals, and making sensible judgments about where the line falls.

HMRC has stated that it will interpret the rules in a ‘reasonable and proportionate’ way but that’s cold comfort if it’s been unable to provide written guidance to date.  To take a fairly obvious question: if one accountancy firm has a tax team of 10 and another has a tax team of 1000, is HMRC expecting there to be significantly more ‘relevant individuals’ in the latter?  Do you count the entire cohort of senior practitioners, each of whom will have some measure of delegated responsibility and authority?  Or do you pick the handful of managers at the top of the tree?

What Now?

Registration has started.  Despite lots of sector requests, we have no reason to expect the imminent release of lots of helpful guidance from HMRC.  So right now, there’s no good reason to wait.

Firms which offer tax advice (according to the legislation’s very broad definition) need to

  • review the shape of their team / tax advisory functions
  • identify relevant individuals
  • contact those individuals to get assurance that they meet HMRC’s standards
  • get on and register.

Helpful links:

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