HMRC’s new Mandatory Registration and Conduct Rules for Tax Advisers will apply from April and May 2026, directly affecting how you support your clients.
These changes introduce a new regulatory framework for organisations that interact with HMRC on behalf of clients and are therefore directly relevant to professional services firms such as accountancy practices, tax advisers, law firms, payroll bureaux, bookkeeping providers and other intermediaries offering paid tax-related services.
You may wish to review the summary below to assess how the new requirements could affect your clients.
Mandatory registration of tax advisers
From 18 May 2026, HMRC will introduce a new online registration system for agent services accounts (ASAs). Registration will be required for any organisation that:
- Interacts with HMRC about another person’s tax affairs, and
- Is paid for doing so
HMRC treats such organisations as tax advisers regardless of how their services are described. Interaction includes phone, email, post, GOV.UK messaging and filing returns or claims. Registration applies to the legal entity, not individual employees.
Organisations with an existing ASA
If your client already has an ASA, you will not need to register again.
HMRC will contact them through their ASA if they require further information to confirm whether your clients meet the new conditions.
Organisations without an ASA
If your client does not currently have an ASA, they will need to register through the new online service once your registration window opens. Please see further details below.
How the new system differs from the current ASA process
The current ASA is simply an access account.
The new regime introduces a mandatory regulatory registration, including:
- Full organisational registration
- Disclosure of senior individuals
- Registration of intermediaries who contact HMRC for clients
- Defined registration windows and deadlines
- Potential sanctions for noncompliance
This represents a significant shift from the existing system.
Where your clients can register
The new registration service will be available on GOV.UK from 18 May 2026.
Intermediaries
Registration is required where an intermediary communicates with HMRC on behalf of clients and is paid for the work.
Registration is not required where an intermediary provides software, payroll, bookkeeping or administrative support without contacting HMRC for clients.
Some organisations may fall within scope even if they do not consider themselves tax advisers.
Senior individuals HMRC will check
HMRC will require details of senior individuals such as partners, directors, LLP members, senior managers responsible for tax work and those with significant control.
- Five officers or fewer: disclose all officers
- Six or more officers: disclose all officers involved in tax work or overseeing it. If fewer than five individuals fall into this category, additional officers must be nominated to reach five. If more than five officers are involved in tax work, all must be disclosed
Who does not need to register
Registration is not required where organisations:
- Only handle tax matters for their own employees or group
- Provide tax advice free of charge
- Interact with HMRC because the law requires it (e.g., insolvency practitioners)
- Provide payroll, accounting or tax software without interacting with HMRC
It is also not required where interaction relates solely to customs, import VAT, VAT representative services, Northern Ireland tax representation, Vaping Duty or appeals to courts or tribunals.
Registration timetable
- 18 May 2026: most advisers
- 18 August 2026: advisers with existing SA or CT accounts
- 18 November 2026: advisers providing only third-party payroll services
Organisations have three months from their applicable date to complete registration.
Consequences of not registering
Failure to register may result in:
- Inability to interact with HMRC on behalf of clients
- A formal stop notice
- Temporary or permanent bans from registering
- Penalties for acting after a stop notice
Conduct rules (from 1 April 2026)
Key changes include:
- HMRC must have reasonable grounds before issuing a file access notice
- Notices must relate to specific clients
- Conduct notices may be withdrawn or will lapse if no penalty is issued within the statutory timeframe
If you would like to discuss how these changes may affect your organisation, please get in touch.