What to do if your tax agent business is changing
Source: gov.uk (2025-09-14)

What you need to tell HMRC if you’re a tax agent and your business is changing in some way.

If your business is changing legal entity

Your tax agent firm is a legal entity if it has any legal rights and responsibilities, including tax filings.

If your business is changing legal entity for any reason, such as changing from a sole trader to a limited company, there are some things you must do.

If you’re using an agent services account

You’ll need to:
- create a new agent services account (https://www.gov.uk/guidance/get-an-hmrc-agent-services-account) for the new legal entity using your new Unique Taxpayer Reference
- get authorisation from your clients (https://www.gov.uk/guidance/how-to-get-authorised-to-act-as-a-tax-agent-on-behalf-of-your-clients) again
- deauthorise any clients not moving to the new legal entity
- write to the Agent Compliance Team to remove your original agent services account against the old legal entity
You must not try to move agents codes from your old legal entity to your new agent services account. This breaches the HMRC standard for agents (https://www.gov.uk/government/publications/hmrc-the-standard-for-agents/hmrc-the-standard-for-agents) and UK General Data Protection Regulation (UK GDPR).

If you’re using HMRC online services for agents

For Self Assessment and Corporation Tax you’ll need to:
- write to the Agent Compliance Team to request new agent codes
- ask the Agent Compliance Team to remove any agent codes for legal entities that are no longer trading or supervised for anti-money laundering
For other duties, request new agent codes (https://www.gov.uk/guidance/find-out-how-to-register-as-a-professional-tax-agent-with-hmrc).

HMRC may ask for more information when you change your agent contact details (https://www.gov.uk/guidance/updating-your-tax-agent-contact-details-with-hmrc). This is to make sure the new legal entity still meets the registration requirements, like supervision for anti-money laundering.

If your agency firm is merging with another one

If your agency firm is merging with one or more other agency firms, you must let HMRC know about the new business set up.

If a new legal entity has been created, you must:
- register it as a business (https://www.gov.uk/set-up-business)
- follow the steps for what to do if your business is changing legal entity
- apply for new agent codes if you’re using HMRC online services for agents
If one agency firm has merged into an existing firm which does not change legal entity, you do not need to do anything with the clients of the existing firm.

For the clients of the merged firm, you must:
- get authorisation from your clients (https://www.gov.uk/guidance/how-to-get-authorised-to-act-as-a-tax-agent-on-behalf-of-your-clients) again for the new firm
- ask the Agent Compliance Team to remove any agent codes for the legal entity that’s no longer trading
If you want to move clients between client lists

When you need to get new authorisation from your client, you do not need to remove your current authorisation first. This will automatically remove the old one.

If you want to move clients between client lists, you must:
- get authorisation from your clients (https://www.gov.uk/guidance/how-to-get-authorised-to-act-as-a-tax-agent-on-behalf-of-your-clients) again
- remove any clients that you do not want to move over
HMRC will not move clients between client lists for you.

If your agency is de-merging from another one

If your agency firm is separating into 2 firms, you’ll need to:
- create a new agent services account (https://www.gov.uk/guidance/get-an-hmrc-agent-services-account) for any new legal entity
- get authorisation from your clients (https://www.gov.uk/guidance/how-to-get-authorised-to-act-as-a-tax-agent-on-behalf-of-your-clients) that need to be moved over against any new entity
- get new agent codes for any new legal entity
Any firm that’s not changing legal entity does not need to:
- create a new agent services account
- obtain new agent codes
- get new client authorisations
If you stop trading as an agent

You must remove all your clients on both:
- your HMRC online services account
- your HMRC agent services account
You must also write to the Agent Compliance Team to tell them you have stopped trading. Include these details:
- your name
- business name
- business address and postcode
- the date you stopped trading, known as the ‘date of cessation’
- agent code or codes, from your HMRC online services account
- agent reference number (ARN), from your HMRC agent services account
If your business dealt with employer PAYE, individual PAYE or both

You’ll also need to send a list of your clients to the Central Agent Authorisation Team. Post it to this address:

National Insurance Contributions and Employer OfficeHM Revenue and CustomsBX9 1ANUnited Kingdom

For employer PAYE, include these details for each client:
- business name
- employer PAYE reference number
For individual PAYE, include these details for each client:
- name
- National Insurance number
Write to the Agent Compliance Team

If you need to contact the Agent Compliance Team, write to:

Agent Compliance TeamHM Revenue and CustomsBX9 2BGUnited Kingdom