Mandatory Agent Registration - Do in-house tax teams need to register?
Martyn Gordon · Posted on: March 5th 2026 · read
New legislation coming into force when Royal Assent is given to Finance (No. 2) Bill 2025-26, will require tax advisors to register in order to correspond with HMRC.
Whilst this was anticipated to have an impact on professional firms, the broad drafting of the rules and limited scope of exemptions have raised concerns that, in some instances, in-house tax professionals may also be required to register.
The Rules
From 18 May 2026 registration will open for those who do not already have an Agent Services Account and after a three-month transition period (to 18 August 2026), tax advisers will be legally prohibited from dealing with HMRC unless they are registered (note, this deadline may be extended for those with an existing CTSA account).
Sanctions for corresponding with HMRC whilst unregistered include financial penalties and potentially a prohibition from corresponding with HMRC in the future.
To register, advisers (organisations and named relevant individuals) must meet certain requirements, including compliance with their own tax obligations, registration for anti‑money laundering supervision, and the absence of any banning orders or HMRC imposed anti-avoidance sanctions. Relevant individuals in this context are the key officers or employees at an organisation who are responsible for overseeing and delivering tax advice, see HMRC Guidance for more details.
The policy is being brought into force to restrict the activities of rogue advisors and raise standards in the tax advice market.
The rules as they stand are, however, very widely drafted and there is concern that they may catch and create administrative burdens for in-house tax teams.
Who is considered an advisor?
The latest draft of Finance (No. 2) Bill 2025-26 defines tax advisor as:
“an organisation that, in the course of a business carried on by it, assists other persons with their tax affairs” (cl221)
The clause goes on to describe ‘assistance’ as any advice or help with any document likely to be relied on by HMRC. A definition which HMRC acknowledge may apply even if: “you do not view yourself as a tax adviser, or describe your work as tax advice”
(HMRC Guidance).
The drafting is therefore wide and is capable of catching a very broad range of activities. There are, however, some exemptions.
Exemptions
Exemptions are available to ensure that the legislation does not catch unintended parties, for example those helping friends or family with tax returns, charitable services offering free advice and insolvency practitioners required by law to interact with HMRC.
An exemption also exists for in-house tax teams who deal solely with payroll for their own employees or the tax affairs of their company or its fellow group undertakings.
Limitations
The exemption noted above is welcome and will cover many of the activities of in-house tax teams, but it is quite narrowly worded and may not anticipate the full spectrum of activities which these professionals undertake across complex business operations.
For example, the definition of group in the exemption derives from the Companies Act (s1161), which defines group undertakings in terms of a parent and subsidiary relationship (e.g. it requires majority control / ownership to be exercised by one party). Whilst this may cover many entities in a corporate group it may not cover, for example, joint ventures (JVs).
If JVs fall outside the exemption, groups operating in sectors where JVs are commonly used like construction, infrastructure, media plus oil and gas may be caught. This could mean the company employing the tax team will have to register as tax advisors, give details of relevant individuals and meet registration requirements, in order to ensure JVs can meet their tax obligations.
This requirement could become onerous in a group with many joint operations, or in one which is actively pursuing new ventures. Not least because questions about which JV partner(s) should register and who are the relevant individuals will need to be addressed.
Complications may also arise for groups with internationally mobile employees. Whilst HMRC’s guidance specifically mentions running payroll for your own staff as exempt, interactions which in-house teams may have on behalf of employees on international assignment e.g. applying for NIC 1A Certificates, do not appear to be covered by an exemption.
Again, if agent registration is required for groups where the in-house tax team deals with tax issues arising from internationally mobile workers, this could cause a significant amount of administrative work to ensure ongoing compliance with the rules.
"It is our view that the examples above are not the sort of HMRC interactions which the legislation is intended to catch. Nonetheless, at present, a strict reading of the law and the absence of any guidance from HMRC to the contrary does suggest that the in-house tax teams would be at risk of falling foul of the rules if they did not register."
Will the exemptions be widened?
Concerns about the breadth of the rules and the limited scope of exemptions have been raised with HMRC through various professional bodies and forums and we understand that HMRC are working on more guidance to clarify some of the issues raised.
We cannot, however, anticipate the tenor of this guidance and whether HMRC view the examples above (and others like them) as situations where exemptions should apply.
Whilst we can hope that HMRC will take a common-sense approach, and that guidance will be delivered swiftly, in the meantime groups may wish to identify whether their in-house tax professionals:
Provide any services to entities which may fall outside the strict definition of group undertakings.
Have correspondence with HMRC on employee tax matters outside of regular payroll compliance.
This will mean if the guidance issued is unhelpful, they will be in a position to process any registration requirements quickly.
If you have any concerns about the new rules coming into force or would like to discuss how your business may be impacted, please get in touch with the team at MHA, we would be happy to help.
