What is a 64-8 form for HMRC?
Answered 17 March 2026
Based on the retrieved sources, here is what a form 64-8 is:
What the Law Says
The retrieved sources do not include primary legislation specifically defining the form 64-8. However, the Upper Tribunal decision confirms its legal effect: it constitutes a formal authorisation by a taxpayer granting their agent authority to act on their behalf "in connection with any matters within the responsibility of HMRC".
HMRC Guidance / Practice
A form 64-8 is HMRC's standard agent authorisation form. It allows a taxpayer (individual or company) to formally appoint a tax agent (such as an accountant or tax adviser) to act on their behalf with HMRC. Specifically:
- What it authorises: It allows HMRC to "exchange information about you with your agent, and to deal with them on any matters within the responsibility of [HMRC]".
- Effect on correspondence: Once received, HMRC will start sending letters and forms to the agent rather than the taxpayer directly, though HMRC may sometimes need to correspond with the taxpayer as well as, or instead of, the agent.
- How it can be submitted: Authorisation can be given on paper or electronically (e.g. via the CT Online Service for Corporation Tax matters).
- Where to send it: In most cases, completed forms are sent to HMRC's Central Agent Authorisation Team (CAAT) at Longbenton, though exceptions apply — for example, if it accompanies a VAT application it goes to the VAT Registration Unit, or if it is solely for Corporation Tax it goes to the relevant HMRC office.
- Death of a taxpayer: A form 64-8 granted by a deceased person ceases to be valid after death. A new form 64-8 must be submitted by the personal representative if they wish the agent to continue acting.
- Welsh version: A Welsh language version of the form exists and must be sent to the Porthmadog office for processing.
In summary, the 64-8 is the cornerstone document by which HMRC recognises a taxpayer's appointed agent and begins dealing with that agent on the taxpayer's behalf.
Citation sources
If an agent or other person was acting on behalf of the deceased prior to their death, for example with the customer’s consent (such as a form 64-8) or through a power of attorney, you may no longer disclose confidential information to these third parties. If the personal representative wants these third parties to continue to act they must authorise HMRC to disclose with a new fresh form 64-8 or other letter of consent. See IDG30210 for guidance on consent. Top of page
de the scope of this letter, for example dealing with Inland Revenue enquiries into your tax return, then this will be a separate engagement for which additional fees will be chargeable.” 8. The letter also asked Mr Tinkler to sign and return a form 64-8 authorising the Inland Revenue to send BDO copies of formal notices. The letter stated that the effect of signing the form was that: “In practice the Inland Revenue will treat this as authority to correspond with us, in which case they will not
The notes on the back of the form 64-8 tell individuals and agents where to send the completed form 64-8. In most cases the forms should be sent to CAAT at Longbenton but there are some exceptions listed. If the form accompanies other correspondence or has been specifically requested by an HMRC office, the customer should send it back to that office. If the form is solely for Corporation Tax affairs, the customer should send it back to the HMRC office that deals with that company. If it is for a
on the faith of any such representation, to the same extent as if such other person had the authority that he was represented to have, even though he had no such actual authority.” 40. In paragraph 8-011 of Bowstead, the authors observe that the English version of the doctrine is plainly based on the notion of a representation by the principal. It follows, therefore, that, in considering the scope of BDO’s apparent authority, what matters are the representations made by Mr Tinkler to HMRC and no
A person or body can be appointed to act as an agent for a company. HMRC only communicates with an agent in writing or over the telephone if we have received a form 64-8 giving us authority to do so and the ‘64-8’ signal is set on the COTAX record. We also accept online returns from an agent, whether or not the ‘64-8’ signal is set. Authorisation on form 64-8 can be given on paper or electronically using the CT Online Service. As long as an agent has a COTAX agent record, they can submit a retur