How to authorise your accountant to deal with HMRC

The main job of an accountant is to look after your limited company’s tax affairs. When you sign up with a new firm, you must give them the authority to deal with HMRC on your behalf. So, how does this authorisation process work in practice?

Permission is given via HMRC’s agent authorisation process. This grants an accountant or tax adviser permission to act on your company’s behalf and deal with:

• Corporation Tax
• VAT
• PAYE (payroll)
• Self Assessment (and other personal taxes)
• Construction Industry Scheme (CIS)

If you’re in the process of choosing a contractor accountant, it’s worth understanding how this works from the outset.

How to appoint an accountant – online and offline

There are several ways to authorise an agent – both offline and online.

a) Submit a paper form 64-8

This is the paper form used to authorise an agent. It will be familiar to anyone who hired an accountant in the pre-digital age. Many firms still prefer this method. You can view a copy here.

Your accountant will typically pre-fill in the required fields on your behalf. If not, you will need to know your company and personal tax reference numbers first, as well as your accountant’s details and agent codes.

Once you’ve signed, you can either scan the signature page and send it back to your accountant to finish the application process, or post the form back directly to HMRC if you can populate all the fields yourself.

b) Your accountant sets you up online

Your accountant can apply for online access to your limited company’s taxes via their HMRC Agent account.

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This generates an activation code for each tax, which will be posted to your company’s registered address.

Once you receive the code, tell your accountant, and the agent authorisation process will be complete.

This usually takes around a week. Make sure you let your accountant know as soon as possible, as each code expires after 30 days from issue.

You’ll have to start the process again if you don’t act promptly, especially if there are postal delays.

In practice, delays often occur at this stage — either because the activation codes are missed in the post or expire before being used. It’s worth keeping an eye out for HMRC letters once the process has started.

c) You authorise your accountant via the Government Gateway

You can also grant authority to your accountant yourself, if necessary.

However, firstly, you need to register your limited company for HMRC Online Services. You can do this here.

You must then select the taxes you want your accountant to handle on your behalf from your Business Tax Account.

HMRC will post codes to your company’s registered office address for each tax, as detailed in option b) above.

Finally, after completing all of these steps, you will be able to appoint an agent to act on your company’s behalf – for each type of tax (CT, VAT, PAYE, and potentially Self Assessment for directors).

d) Digital Handshake – available for certain taxes only

For certain taxes, an alternative online method allows your accountant to deal directly with HMRC. This is known as a digital handshake.

This method is increasingly being used for certain taxes, particularly under Making Tax Digital (MTD), although availability still depends on the specific tax.

For VAT, your accountant may send you a link via email to link your account to their online dashboard.

For all other taxes, authorisation methods a), b) and c) apply.

How to remove authorisation from an agent

You may need to remove authorisation from an accountant in the future – typically when you switch accountants.

Change or remove access online

If you have online access to your HMRC Business Tax Account (see above), you can remove an agent from a specific tax whenever you wish. You can replace them with your new adviser’s details, provided you have their agent code to hand.

Change or remove access offline

If you don’t have access to HMRC online services, you can still make changes or remove an agent, although the process is a little more cumbersome.

You can contact HMRC via phone or post. Read the details here.

In most cases, your accountant will handle this process for you, but it’s still worth understanding how it works — particularly if you ever need to switch firms or revoke access.