UK Mandatory Tax Adviser Registration: What It Means For Inhouse And Asset Management Tax Functions

The UK is introducing a new mandatory registration regime for tax advisers, scheduled to go live from May 2026 (with at least a three‑month transition period). While much attention has centred on the impact for accountancy firms and law firms, the regime reaches far beyond traditional advisers.

Crucially, it will also capture some in‑house tax teams, including those within large corporates, financial institutions, asset managers and family offices.

For many organisations, this marks a fundamental shift. They may not see themselves as "tax advisers"—but the legislation does. And the risks associated with failing to comply with this regime are significant.

Below we summarise the implications and provide a practical, step‑by‑step process to help organisations assess their position and prepare.

Who is a "tax adviser"? Why in‑house teams may be affected

The definition in the legislation is intentionally broad. A "tax adviser" is any organisation or individual (carrying on business as a sole trader) that:

Assists others with their tax affairs, including advising, acting as an agent or helping prepare documents likely to be relied on by HMRC to determine tax positions.

For corporate groups and asset managers, this means the following may fall within scope:

• Centralised tax functions serving multiple group entities
• Asset management tax teams preparing fund or investor tax filings
• Tax operations/oversight teams reviewing documents later submitted to HMRC
• Global mobility or payroll teams interacting with HMRC on behalf of employees
• Any function that interacts with HMRC regarding a different group company's affairs (unless the specific group exception applies—see below)

This is a functional rather than a professional definition. Even if tax is not your core business, and you have no formal tax qualifications, you may still technically be a "tax adviser" for registration purposes.

The group-company exception—helpful but limited

There is an exception where an adviser interacts with HMRC only in relation to a client that is part of the same corporate group.

This will exempt many routine in‑house adviser–HMRC interactions. But:

• If the in‑house team also advises non‑group entities (e.g., JV vehicles, funds, or portfolio companies), the exception will not apply.
• Asset managers often manage structures outside the core corporate group, meaning their tax teams are likely to still fall in scope.

This is therefore clearly not a blanket exemption for all in‑house teams, and even a small amount of activity outside of the exception will mean that the obligation to register before any interaction with HMRC remains.

It is important to note that the test of a group in this context is different from the test for grouping for many other tax purposes. It uses the Companies Act definition of "group undertaking" which has its own specific criteria (focusing on voting rights and ability to appoint directors rather than beneficial ownership).

Conditions organisations and "relevant individuals" must meet

To register, both the organisation and each of its relevant individuals must satisfy a set of conditions, including confirming that they:

• Have no overdue tax or outstanding UK returns
• Have no disqualifying anti‑avoidance history (e.g., stop notices, DOTAS penalties)
• Are not subject to HMRC restrictions, ineligibility orders or suspended status
• Are not disqualified directors
• Do not have unspent convictions for certain tax‑related offences

The adviser must also be AML‑registered, where required

"Relevant individuals" include those who:

• Make decisions about how the organisation's tax adviser activities are managed; or
• Manage a substantial part of those activities.

Tax Adviser Activities are not defined (and whilst the draft legislation is not clear, it is hoped that this will be clarified to refer only to the activities involving tax advice).

In practice, this could include:

• Heads of tax
• Senior tax managers overseeing compliance processes
• Directors of the company
• Partners in a partnership or LLP
• Other individuals who exercise functions of management (depending on the legal form of the organisation and the governance structure).

The draft legislation is complex and identifying the relevant individuals (or where there is a choice, nominating appropriate individuals) may not be straightforward.

Correctly identifying these individuals is likely to be one of the most complex steps for large organisations. Given that the conditions need to be satisfied by such individuals in their personal capacity as well as a business capacity, this is also an HR issue and any vetting process will need to be managed.

Practical risks for corporate groups and asset managers

1. The compliance burden sits across both the entity and individuals

Failing any condition can block registration or lead to suspension later.

2. HMRC monitoring continues after registration

HMRC can request information on an ongoing basis to check the conditions remain satisfied so appropriate monitoring processes will need to be put in place and maintained.

3. Penalties for getting it wrong are significant

Interacting with HMRC while unregistered can trigger:

• Compliance notices
• Penalties of £5,000–£10,000 per offence
• Publication of adviser details
• Ineligibility orders preventing future registration

If a tax adviser is suspended, then the tax adviser must notify each client, with a penalty of £5,000 per client for failure – thereby also exposing the business to relationship, contractual or reputational risk.

A straightforward process for organisations to assess and prepare

Below is a simple, practical framework your organisation can use immediately.

Step 1: Map your tax adviser activities

Create an internal inventory of all activities that may constitute "assisting others with their tax affairs".

Consider:

• Who prepares or reviews documents later provided to HMRC
• Who interacts with HMRC for entities other than the one employing them
• Cross‑border teams supporting UK filing requirements
• Teams supporting funds, portfolio companies, JV entities or SPVs

Output: a clear view of where the regime may bite.

Step 2: Assess whether the group‑company exception covers your activities

For each activity mapped:

• Is it only in relation to a legal entity in the same corporate group?
• Do tax teams act for funds, investors, JV entities or external JV partners or on behalf of employees?
• Are any tax interactions carried out through a service company structure or fully outsourced?

This step determines which functions may need registration

Step 3: Identify your "tax adviser organisation(s)"

Consider which entities the functions identified above are employed be. A group may have:

• One tax adviser organisation (centralised tax function),
  or
• Multiple—e.g., separate entities providing tax support to funds or SPVs.

Define which legal entity/entities may be treated as "tax advisers".

Step 4: Identify all "relevant individuals" in those tax adviser entities

For each adviser organisation:

• Determine if it has more or less than six officers (broadly, directors or partners)
• List the individuals responsible for tax governance and oversight.
• Include senior executives holding management authority over tax functions.

Having done so, consider if you also need to select additional officers of the organisation to act as relevant individuals in order to meet the requirements of the regime.

Getting this step right is critical: those individuals must also meet all registration conditions.

Step 5: Pre‑screen against the registration conditions

Undertake a confidential internal check that:

• No relevant individuals have overdue tax, outstanding filings, insolvency issues or disqualifications
• The organisation meets all AML registration requirements
• There are no anti‑avoidance notices or penalties that could disqualify registration

Where issues exist, early remediation is essential before May 2026.

This will involve asking individuals potentially sensitive questions and will need to be handled carefully.

Step 6: Develop an internal policy and governance process

To ensure ongoing compliance:

• Add controls to prevent any HMRC interaction by unregistered advisers
• Establish monitoring and periodic internal attestations for relevant individuals
• Update internal HMRC‑facing protocols
• Train staff on when interactions trigger the regime

Step 7: Monitor HMRC updates

HMRC will publish more guidance and the application process imminently.
Assign internal responsibility for tracking updates and coordinating registration.

Consider any need to update internal systems to identify HMRC interactions which are within the regime.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.