The 64-8 form, explained

What the 64-8 lets a tax agent do for you, how to fill it in, and what it doesn’t cover.

Last checked against HMRC and MOD guidance on 13 November 2026.

The 64-8, full name "64-8 Authorising your agent", is the HMRC form you sign to let a professional accountant, tax adviser or other paid agent deal with HMRC for you.^[1] If you claim a tax refund through a company like us, you'll usually be asked to authorise us this way or online.

What it lets an agent do

For Income Tax and PAYE, authorising an agent gives them access to information including:^[1]

• your past employers
• taxable benefits
• pensions
• the dates you started and stopped being on PAYE

For Self Assessment, an authorised agent can submit returns, claim reliefs and view or change your details.^[1]

Online first, paper if you can't

HMRC asks people to authorise agents online where they can. You only need the paper 64-8 if you can't authorise your agent through an online service or your business tax account.^[2] In practice, many agents send you a request to approve online.

How to fill in the paper form

1. Download the 64-8 from GOV.UK and open it in the latest free Adobe Reader.^[1]
2. Fill it in on screen, or print it and fill it in by hand.
3. Your agent fills in their own details and agent codes.
4. Sign and date it. HMRC updated its guidance in July 2026 to make clear the form must be signed and dated.^[2]
5. Post it to HMRC at the address on the form.^[1]

HMRC also asks you to write clearly, keep everything inside the boxes, not cross out unused boxes, and not add a covering letter unless it contains something essential.^[1]

What it doesn't do

• It doesn't make the agent responsible for your tax. You stay legally responsible. If an agent sends a return for you, you should check it's correct first.^[1]
• It can't be used for limited authorisation. HMRC no longer accepts the 64-8 for that.^[1]
• It isn't for compliance checks. These use form COMP1a.^[1]
• It doesn't by itself send your refund to the agent. For a P87 claim, a refund is only paid to someone else if you nominate them in the nomination section of the form.^[3]

The 64-8 and your Forces Money claim

We send you the authority to sign as part of your application. Once we've confirmed we've accepted it, you have 14 days to change your mind, no reason needed. You'll also approve your claim before anything goes to HMRC. See our terms.

Questions