How to Authorise an Accountant or Agent to Deal with HMRC for You (2026/27)

This guide is general information, not advice.

This guide is for sole traders, landlords, company directors and anyone else about to hand their tax to an accountant or tax agent, or to let a relative help. HMRC will not deal with anyone on your behalf until you have authorised them, and how you do that depends on the tax. GOV.UK’s authorising an agent guidance puts it simply: your agent will tell you how.

By the end you will know which of the three routes your agent is asking you to use, what to click, what the agent will then be able to see, and how to take the access away again.

Before you start

• Your own sign-in for the tax in question. The link from your agent has to be opened with the sign-in details you use for that tax service. GOV.UK warns you may have more than one account, so use the right one.
• Your references: your Unique Taxpayer Reference and National Insurance number for Self Assessment; your company’s UTR and registration number for Corporation Tax; your VAT number; your employer PAYE reference.
• The agent’s details: their business name and address, and for form 64-8 their agent codes. For the business tax account route you need their Agent Government Gateway Identifier.
• Registration first. GOV.UK says you must register for Self Assessment before you authorise an agent for it.

Step-by-step

1. Ask your agent which route they will use. The appoint someone page says you must authorise your agent before they can deal with HMRC and that they will tell you how to do this. Never hand over your own login instead: GOV.UK says you must not give your sign in credentials to your agent or anyone else.

2. Route 1: accept the digital handshake link. For the taxes listed on Authorise an agent for taxes that use the digital handshake

   • including Making Tax Digital for Income Tax, VAT, a Capital Gains Tax on UK property account, managing a trust or estate, and the Income Record Viewer - your agent creates an authorisation request and emails you a link. Select it, sign in with the details for that tax, and verify your identity if asked. The link expires after 21 days. For Making Tax Digital for Income Tax, GOV.UK says your agent can only sign you up if you have registered for Self Assessment and already submitted a tax return; otherwise you sign up yourself and tell them.

3. Route 2: add the agent in your business tax account. For employer PAYE, the Construction Industry Scheme, VAT and a handful of duties, the business tax account guidance gives the clicks: sign in, select Manage account, under Tax agents select Add, view or change tax agents, choose the tax, select Add an agent, enter the agent ID, check the details and select Add agent. For Self Assessment and Corporation Tax, the same page says to talk to your agent about how they can get authorised.

4. Route 3: the paper form 64-8. If you cannot use an online route, the guidance points you to the 64-8 Authorising your agent form. It has boxes for Self Assessment, partnership, trust, individual PAYE, Corporation Tax, tax credits, VAT, the VAT DIY Housebuilder Scheme, CIS and employer PAYE. Tick only what you want: the form says the authorisation is limited to the matters indicated. Give the correct agent code for each regime (the Self Assessment agent code is 6 characters), write nothing outside the boxes, sign, date and post it to the address on the form. Use one form per agent. It overrides any earlier authority.

5. Know what the 64-8 cannot do. The form says that if you have signed up for Making Tax Digital for VAT it cannot authorise an agent for those services. For trusts, the guidance says a 64-8 does not give the agent access to the online service. For a compliance check, the form is COMP1a instead.

6. Check what your agent can now see. For Self Assessment, the guidance lists: submitting returns, making relief claims, discussing current and previous returns, changing your details, giving HMRC bank details for a repayment, viewing calculations and amounts owed and paid, and even cancelling your registration. An MTD for Income Tax agent can also keep your digital records and send quarterly updates. The appoint someone page says HMRC will send Self Assessment correspondence to the agent except tax bills or refunds; on a 64-8 you can tick a box to have your Statement of Account sent to the agent instead.

7. Keep checking the return. GOV.UK is clear that you are still legally responsible for your own tax, and that you must check the information in your return and tell your agent it is correct before they submit it.

Help from a friend or relative instead

A relative helping for free is not an agent. They register as a trusted helper. They can check you are paying the right Income Tax, check or update your personal tax account and taxable benefits (company cars or medical insurance only), check your State Pension and view your National Insurance record. You must accept their offer within 28 days, and they can then help online for 90 days before registering again. One person can help up to 5 people. A trusted helper cannot help with Self Assessment.

If you cannot go online, they can call HMRC for you as long as you are in the same room. For longer arrangements the appoint someone page also covers authorising an intermediary by letter and registering a power of attorney.

How to remove or change an agent

GOV.UK’s change or remove guidance says a new authorisation request replaces any existing authority, so to switch accountant you simply authorise the new one. To remove access without a replacement:

• Digital handshake taxes: sign in to your personal tax account and select Profile and settings (or Manage account in a business tax account), then View agent account history or remove a tax agent, Who can deal with HMRC for you, Remove authorisation, Yes, Continue.
• Other taxes, including Self Assessment and Corporation Tax: in your business tax account go to Manage account, Add, view or change tax agents, pick the tax, manage agents, remove, remove agent.
• By post: write to the Central Agent Authorisation Team at the address in the guidance with your name, the agent’s name and address, their agent code if known, and your tax reference for each service.

Deadlines and what happens next

• The agent’s link expires 21 days after it is sent.
• A trusted helper request must be accepted within 28 days and lasts 90 days.
• The guidance does not give a processing time for a posted 64-8. HMRC’s check when you can expect a reply tool, updated weekly, lets an agent check how long HMRC is taking to process an application for authority to act for a client, so ask yours.
• The 64-8 itself warns HMRC may contact you in future to reauthorise the relationship.

Paid advisers are also now legally required to register with HMRC, with the requirement introduced in stages; what that means for you is in our tax adviser registration guide.

Common mistakes

• Sharing your login. GOV.UK says you must not give your sign-in details to anyone, and an agent must not use a client’s credentials.
• Removing an agent from Self Assessment but not MTD for Income Tax, or the other way round. GOV.UK says to remove them from both.
• Sending a 64-8 for MTD for VAT. The form cannot do it.
• Using a trusted helper for a Self Assessment return. The service does not cover it; the helper would need to call HMRC with you, or you would need an agent.
• Letting the 21-day link lapse. Ask for a new one rather than trying an old link.

Related reading

• HMRC tax adviser registration 2026 - what to ask your accountant under the new rules.
• Personal tax account guide - where your authorisations and records live.
• Contractor accountant guide 2026/27 - choosing an accountant before you authorise one.