- A 64-8 form authorises a paid accountant to deal with HMRC for you.
- HMRC calls online authorisation easiest; the paper 64-8 is the fallback.
- You stay legally responsible for your tax after authorising an agent.
A 64-8 form is HMRC’s paper form for authorising an accountant or tax agent to deal with HMRC for you. Signing one is how you formally appoint a limited company accountant to file returns and handle HMRC on your company’s behalf.
This guide covers what the form includes, how to complete and send it, and when to authorise online instead.
What does the 64-8 form do?
Form 64-8 gives formal permission for an accountant or tax agent to deal with HMRC for you. HMRC won’t discuss your tax affairs with anyone it hasn’t authorised, so without it your accountant can’t act for you.
Once HMRC accepts the form, your agent can:
- file returns and claim reliefs on your behalf
- access your records for the taxes you’ve authorised
- discuss payments, repayments and queries directly with HMRC
The HMRC 64-8 form covers Corporation Tax, Self Assessment, employer PAYE, individual PAYE and National Insurance, and VAT dealings in writing or by phone. It’s a key step, because it lets your accountant handle your company’s tax while you get on with running the business.
If you’re setting up a limited company, it’s worth authorising your accountant as soon as you register. Our guide to company registration walks through that first step.
Which taxes does the 64-8 form cover?
Each area of agent authorisation is separate, so you choose exactly what access to grant. Here’s what your agent can do for each tax once HMRC has processed the form.
Self Assessment
Your agent can submit returns, claim reliefs, view your calculations and discuss current and past returns with HMRC. They can also give HMRC your bank details when a repayment is due, or cancel your registration.
You’ll need to be registered for Self Assessment before you can authorise an agent for it.
PAYE for employers
For employers, a 64-8 gives your agent access to your PAYE records, including your employees’ personal and financial information. That lets them deal with payroll queries, tax codes and deductions with HMRC.
Corporation Tax
When authorised for Corporation Tax, your accountant can access your company and financial information and update its contact details with HMRC. That’s what lets them prepare your CT600 and handle payment or penalty queries.
To understand how trading status affects your filing duties, see trading vs non-trading for Corporation Tax.
VAT
A 64-8 only lets your agent deal with HMRC about VAT in writing or by phone. To submit VAT returns under Making Tax Digital, your agent needs separate authorisation through HMRC’s digital handshake.
If a payment does slip, our guide to VAT late payment penalties explains what happens next.
Construction Industry Scheme (CIS)
HMRC’s authorisation table for agents lists CIS as an online-only authorisation, set up through Online Agent Authorisation or your business tax account. Once authorised, your agent can access your CIS returns and your subcontractors’ income and deductions.
Keep a digital copy of your signed 64-8 so you can update or replace your authorisation quickly later.
How do you complete the 64-8 form?
Filling in the 64-8 form is quick once you know what HMRC needs. It’s in three parts: your details, your agent’s details, and the taxes they’ll handle.
Step 1: Add your personal or company details
Start with your name or company name, address and contact details. Then add the tax reference numbers HMRC holds for each tax you’re authorising, such as your UTR, VAT number or employer PAYE reference.
These must match HMRC’s records exactly, as even small mismatches slow processing down.
Step 2: Provide your agent’s information
Next, enter your accountant’s business name and address, plus their HMRC agent code for each tax. For Self Assessment, the code is 6 characters in the format 1111XX. Without the right code, HMRC can’t link the authorisation to your agent.
If you’re still choosing a professional, Sleek’s accounting services include HMRC authorisation setup as part of onboarding.
Step 3: Select the taxes your agent can handle
Tick each area you want to authorise. You can authorise more than one tax on the same HMRC 64-8 form.
- For Corporation Tax, include your company’s UTR (see our guide to finding your UTR if it’s not to hand).
- For VAT, include your VAT registration number.
- For employer PAYE, include your employer PAYE reference.
Step 4: Sign and date the form
You must sign and date the form yourself before you send it. If you’re authorising on behalf of a company, the signature should come from someone who can act for it, such as a director.
Step 5: Check before you send
HMRC asks you to:
- type or write clearly, keeping everything inside the boxes
- leave unused boxes as they are, without striking them through
- include only the information each field asks for
- skip the covering letter unless it holds something HMRC needs to process the form
A final check saves you a rejected form and a second wait.
How do you submit the 64-8 form to HMRC?
You can authorise an agent online or post a paper form 64-8. HMRC says online is the easiest route, and the paper form is for when online authorisation isn’t possible.
Online authorisation
For Corporation Tax, Self Assessment and employer PAYE, your accountant requests access through HMRC’s Online Agent Authorisation service. HMRC then posts you an authorisation code within 7 working days, which you pass to your accountant within 30 days.
Each tax gets its own code, so keep track of which is which. If the code expires, the process starts again.
For VAT and Making Tax Digital for Income Tax, your accountant sends you a link instead, and you approve it by signing in to your HMRC account.
Postal submission
Download the latest form from GOV.UK and post it to the address shown on it, which for most authorisations is HMRC’s Central Agent Authorisation Team. If the authorisation is for Corporation Tax only, send it to the HMRC office that deals with your company’s Corporation Tax instead.
After submission
Once HMRC processes the authorisation, your accountant can act for you on the taxes you selected. If anything doesn’t match HMRC’s records, expect a query before it goes through.
How long does a 64-8 take to process?
Online authorisation is usually the faster route. The code letter arrives within 7 working days, and the authorisation is active as soon as your accountant enters the code.
Paper forms depend on HMRC’s postal processing times. For an up-to-date estimate, use HMRC’s reply-time checker, and ask your accountant to chase if that date passes.
What can an authorised agent do, and what can’t they?
A 64-8 gives your agent permission to act for you, within clear limits.
What your agent can do
Your authorised agent can:
- file returns and claim reliefs for the taxes you selected
- discuss your account with HMRC by phone or in writing
- update your contact details with HMRC
- give HMRC your bank details for a Self Assessment repayment
What your agent can’t do
Authorisation covers only the taxes you selected, and it doesn’t move your legal obligations onto your agent. You stay responsible for your own tax, and you must check and approve any return before your agent submits it.
It’s worth reviewing your authorisations once a year, or whenever your business changes.
How do you change or remove a 64-8 authorisation?
You can remove an agent’s authorisation at any time, whether you’re changing accountant or no longer need one.
How to remove access
For most taxes, sign in to your business tax account and remove the agent under “Manage account”. You can also remove an agent’s authorisation by post, giving your name, the agent’s details and the tax reference for each service.
If you’re removing an agent from VAT or employer PAYE, you’ll also need to write to or call HMRC to stop them dealing with HMRC by phone or in writing.
How to appoint a new agent
To switch, authorise your new accountant online or with a new 64-8. HMRC treats any new authority as replacing the existing one for the taxes it covers.
Why use a professional tax agent?
Authorising a qualified accountant does more than save admin time. It cuts the risk of missed deadlines, wrong filings and HMRC penalties.
A professional agent will:
- file returns and make payments on time
- deal with HMRC correspondence directly
- keep your company compliant as the rules change
That’s time back for the work that grows the business. If you’re weighing it up, our guide on accountant costs for small businesses covers what to expect.
How does digital authorisation fit with Making Tax Digital?
HMRC is moving agent authorisation online. For VAT and Making Tax Digital for Income Tax, your agent uses the digital handshake: they send you a link, and you approve it in your HMRC account.
A paper 64-8 can’t be used for these services. If your accountant manages your MTD submissions, they’ll set this up as part of onboarding.
Companies House runs its own rules for agents, separate from HMRC. If someone files with Companies House for you, see our guide to authorised agent identity verification.
Are there special cases to watch for?
Some situations need extra care when you use the 64-8 form.
Deceased persons and estates
A personal representative can use a 64-8 to authorise an agent for the estate’s individual PAYE, Self Assessment and National Insurance. They sign with their own name and address, and add the deceased person’s National Insurance number or UTR.
Multiple agents
You can use different agents for different taxes, such as one for payroll and another for Corporation Tax. Each agent needs their own authorisation.
Data protection
By signing, you agree that HMRC can share the relevant tax information with your agent. Your agent must then handle that data securely under UK GDPR.
How Sleek helps with your 64-8 form
A 64-8 form is the point where you hand your company’s HMRC dealings to an accountant, so it’s worth choosing one you’ll want to keep. With Sleek’s limited company accountant service, a dedicated, qualified accountant becomes your agent with HMRC, online or by 64-8, then handles your accounts, Corporation Tax and HMRC correspondence from there.
AI does the groundwork on your filings, your accountant checks every one, and you can see what was done and why. Your questions get a same-day reply, so a letter from HMRC never sits waiting.
If all you need is a single Self Assessment return filed, a one-off service may suit you better. For broader questions, our tax FAQs are a good place to start.
Let Sleek be the accountant on your 64-8 form
FAQs on what is a 64-8 form
Does my accountant fill in the 64-8 for me?
Usually, your accountant prepares the 64-8 with their agent codes filled in, and you check it, sign it and date it. Many accountants skip the paper form and request authorisation online, so you just pass on the code HMRC posts to you. Either way, the signature or approval has to come from you.
Is the 64-8 still used?
Yes. The paper 64-8 is still HMRC’s written route for Corporation Tax, Self Assessment, employer PAYE, individual PAYE and National Insurance, and VAT dealings by phone or letter. It can’t be used for VAT returns under Making Tax Digital or for Making Tax Digital for Income Tax, which rely on the digital handshake instead.
Can I authorise an accountant for just one issue?
Yes, through what HMRC calls limited authorisation. You write a signed letter of authority to HMRC’s National Insurance Contributions and Employer Office, giving your name, address, tax reference, and your agent’s name and address. HMRC no longer accepts the 64-8 for this, and an agent with limited authorisation can talk to HMRC and help with forms but can’t see your tax online.
Do I need a 64-8 if HMRC opens a compliance check?
A compliance check uses a separate, temporary authorisation. You fill in form COMP1a to let HMRC deal with your tax adviser on that check, or your adviser can apply online with form Comp1.
Can a friend or relative use a 64-8 to deal with HMRC for me?
The 64-8 is for paid agents, such as accountants and tax advisers. HMRC has a separate process for appointing a friend or relative to help with your tax, so use that route if the person helping you isn’t acting professionally.
Should I give my accountant my HMRC sign-in details instead?
No. HMRC says you must not share your sign-in details with your agent or anyone else, and agents mustn’t use a client’s login. Authorising them properly gives them their own access through their agent account.
Does a 64-8 cover my trust's tax affairs?
A 64-8 can authorise an agent for a trust’s tax affairs, and the form goes to HMRC’s Trusts and Estates team rather than the usual address. It doesn’t give your agent access to the Trust Registration Service, though. For that, you authorise them through the trust’s online registration service.
