Form 64-8: authorising an accountant to deal with HMRC

Who needs it

• Individuals who want a paid adviser to handle Self Assessment and are already registered for it.
• Employees who want an agent to deal with their PAYE affairs.
• Tax credit claimants: for a joint claim, both claimants sign.
• Anyone who can't use HMRC's online agent authorisation or their business tax account.

What you need before you start

• Your name, address and the tax references for each tax you're authorising (for example your UTR and National Insurance number).
• Your agent's name and address, and the agent code they give you for each tax.
• The current 64-8 PDF from GOV.UK and the latest free Adobe Reader if you complete it on screen.

How to file 64-8

1. 1Check first whether your agent can authorise you online. HMRC prefers it, and it's usually quicker.
2. 2Register for Self Assessment before authorising an agent for it. The 64-8 can't be used for a Self Assessment account that doesn't exist yet.
3. 3Download the 3-page 64-8 from GOV.UK and complete it on screen or by hand. Enter the agent code for each tax exactly as your agent gives it.
4. 4Sign and date it. Don't add a covering letter unless it's essential, don't write outside the boxes and don't strike through boxes you don't use.
5. 5Post it to the address printed on the form.

Online first, paper when you can't

HMRC's guidance is to authorise an agent through an online service or your business tax account if you can, and to use the 64-8 only if you can't. The right method depends on the tax, and HMRC lists the options for each on its authorising-an-agent page.

In practice, your accountant will usually start an online request and send you a link or code to approve. The paper form is the fallback for cases the online services don't cover.

What a 64-8 can't do

HMRC no longer accepts the 64-8 for limited authorisation. If you want someone to deal with one specific matter, write to HMRC with your name and address, your tax reference, the agent's name and address, and your signature.

It doesn't cover compliance checks (use COMP1a), it doesn't give access to a trust's online service, and it's only for paid agents.

Completing the form

Each tax has its own agent code box. HMRC's example for PAYE is a code in the format XX1111, and the Self Assessment agent code is six characters. Your agent provides these; you don't need to look them up.

HMRC asks for clear writing, nothing outside the boxes, no extra information and no covering letter unless it's essential. Forms that don't follow this are slower to process.

Common mistakes

• Sending a 64-8 to ask for limited authorisation. HMRC no longer accepts it for that; write a letter of authority instead.
• Using it to authorise an agent for a compliance check. HMRC asks for form COMP1a for that.
• Sending it for Self Assessment before registering. Register first.
• Using it for a friend or relative who isn't paid. It's for paid agents; HMRC has a separate route for someone helping you informally.
• Expecting it to give the agent access to a trust's online service. That has to be set up inside the service.