Form 64-8: how to authorise an accountant to deal with HMRC

What is form 64-8?

Form 64-8 is the paper form you sign to authorise an accountant or tax adviser to deal with HMRC for you. It is still in use. HMRC's guidance on authorising an agent was last updated in October 2026 and still tells people to use it when they cannot authorise online.

But 64-8 is no longer the only route, and for several taxes it is not the first choice. How your accountant gets authority depends on the tax. Your accountant will tell you which route they use and send you what you need.

Which route is used for which tax

This table follows HMRC's guidance on how agents get authorised.

You can authorise for more than one tax on the same 64-8. Online Agent Authorisation no longer covers VAT. That ended on 16 February 2024.

Online route 1: authorisation code by post

This is Online Agent Authorisation. It is used for Self Assessment, Corporation Tax and employer PAYE. Your accountant starts it from their HMRC agent account, so there is little for you to do.

1. Your accountant requests authorisation for each tax in their agent account, using details you give them.
2. HMRC posts a letter with an authorisation code to you, within 7 working days.
3. You give your accountant the code within 30 days. After that it expires and they must start again.
4. They enter the code and you appear on their client list.

You get one code for each tax. If you are authorising Self Assessment and Corporation Tax, expect two letters and make sure your accountant knows which code is which. Three wrong entries means starting again. See HMRC: Online Agent Authorisation.

Online route 2: the client authorisation link

For Making Tax Digital for Income Tax and VAT, HMRC uses the "digital handshake". Your accountant creates an authorisation request in their agent services account and sends you a link. You open it, sign in with your own HMRC details (you can create them if you do not have any) and approve it.

The link expires after 21 days. If it lapses, your accountant sends a new one. Sign in only with your own details and never give your password to anyone. See HMRC: the digital handshake.

For employer PAYE and some other taxes you can also authorise in your own business tax account by entering your accountant's agent identifier. Your accountant will give you the identifier.

The paper route: completing form 64-8

Use 64-8 if you cannot authorise online or the tax has no online route, such as individual PAYE or National Insurance. HMRC's instructions are strict. Forms that break them can be rejected.

• Use the current "64-8 Authorising your agent" form from GOV.UK.
• Type or write clearly.
• Use the agent codes your accountant gives you for each tax. For example, the Self Assessment code has 6 characters in the form 1111XX.
• Do not write outside the boxes or add extra information to fields.
• Do not strike through unused boxes.
• Do not add a covering letter unless it holds essential information.
• Sign and date the form, then post it to the address printed on it.

Download the form from GOV.UK: 64-8.

How long does it take?

For the code route, HMRC says the letter with your code is sent within 7 working days. After you pass the code on, your accountant is authorised once they enter it.

For a paper 64-8, HMRC does not give a fixed turnaround in its guidance. You can use HMRC's tool to check when you can expect a reply. Ask your accountant to confirm when authority is live before relying on it for a deadline. Leave time before 31 January.

What authorising an agent means

For Self Assessment, an authorised agent can file your return, make claims for relief in it, discuss current and previous returns with HMRC, view calculations and amounts owed or paid, and update your details such as sources of income. For Corporation Tax they get access to the company's financial information and can update its contact details. For employer PAYE they can see your employees' personal and financial information.

You stay legally responsible for your own tax. If your agent files your return, you must check the information and tell them it is correct before they submit it. Agent authority does not transfer your obligations to them. If you need a friend, relative or voluntary organisation to talk to HMRC rather than a professional, a letter of authority is a different route. HMRC covers it in appoint someone to deal with HMRC on your behalf.

HMRC will not accept a 64-8 for limited authorisation, where an adviser helps with one area of your tax but is not your full agent. For that, write to HMRC with your name and address, your tax reference such as your UTR, the adviser's name and address and your signature.

How to remove an agent

You can remove an agent if you change accountant, if they retire or if you no longer need one. HMRC sets out the steps in change or remove your tax agent's authorisation.

• Corporation Tax, employer PAYE, Self Assessment and CIS: sign in to your business tax account, go to Manage account, then Add, view or change tax agents. Pick the tax, select manage agents and remove.
• Making Tax Digital for Income Tax, Capital Gains Tax on UK property and other digital handshake services: sign in to your personal or business tax account and use View agent account history or remove a tax agent.
• By post: write to the Central Agent Authorisation Team, National Insurance Contributions and Employer Office, HMRC, BX9 1AN. Include your full name, the agent's name and address, their agent code if you know it, and the tax reference for each service.

Self Assessment and Making Tax Digital for Income Tax are linked: if you remove your agent from one, remove them from the other too. For VAT or employer PAYE, if you want to stop an agent dealing with HMRC by phone or in writing, you must also remove them by post or phone. Individual PAYE and National Insurance authority set up on a 64-8 is removed by post.

Switching accountant

You do not have to remove the old agent first. HMRC says that when you change agent you submit a new authorisation request and any new authority replaces the existing one. In practice:

1. Tell your new accountant which taxes you want them to handle, and give them your tax references.
2. They request authority by the right route for each tax. Pass on any codes or approve any links promptly.
3. Once they confirm they are live, check the old agent is removed from every tax. A new authority replaces the old one, but it is worth checking each tax.
4. Ask the old firm to hand over your records and check nothing is due soon.

Our guide on how to change accountant covers the full handover, including clearance and timing.

Related: if you need help with the sign-in side, see our HMRC online accounts guide.