What is a 64-8?

A 64-8 is an HMRC form that gives your accountant or tax advisor permission to act as your agent.

When you complete a 64-8 your agent can communicate with HMRC on your behalf, complete your self assessment tax return and retrieve some personal information about your tax position.

The 64-8 tells HMRC that you give a third party authorisation to deal with your tax affairs on your behalf. It is an important form because it helps stop fraudulent access to your tax records.

You can sign a 64/8 as an individual, a company, a partnership or a tax trust.

How do I complete a 64-8?

A 64-8 is easy to complete online or by downloading it and sending it to HMRC by post to:

National Insurance Contributions and Employer Office

HM Revenue and Customs


It is important to only tick the relevant areas of tax you would like your agent to help you with.

The areas of tax covered on the 64/8 are:

What information do I need complete a 64-8?

The main information you need to enter on your 64-8 includes:

  • Your name and address.
  • Your national insurance and UTR number.
  • Your contact information.
  • Your agent’s name and address.
  • Your agent’s contact details.

You should take care to include your national insurance number and UTR number where applicable. If you don’t include all of the information requested your 64/8 could be rejected by HMRC.

When should I complete a 64-8?

You should only complete a 64-8 when you are confident that you want to appoint an agent to help you with your tax matters.

Like all authorisation forms that give access to your personal information it is always recommended that you do your own due diligence on the third party before signing the 64-8.

A 64-8 can be removed from your record by contacting HMRC and asking them to remove it. HMRC will update your record meaning the agent you have removed will no longer have access to your records or be able to act on your behalf.

Online agent authorisation

If you are appointing an agent they may not use the 64-8 process and instead use an online authorisation method.

Your agent will ask HMRC to send you an authorisation code by post which you then have to pass on to your agent within 30 days. If you don’t pass on the authorisation code within the stated timescale the code will expire.

The agent you are appointing will use the code to give them the same access to your tax records as the 64-8.

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