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CH201550 - How to do a compliance check: general: Comp1 - temporary authorisation of tax adviser during a compliance check

When the Temporary Authorisation form Comp1 can be used
Guidance and access to form and advice on usage for customers
Extending the compliance check
Action on receipt of form Comp1
Customer who signed the Comp1 or 64-8 is unable to deal with their tax affairs
Caseflow Scanning cases
Non Caseflow Scanning cases
Cross Tax Cases
Data Security


Form Comp1 allows customers to temporarily appoint a tax adviser to act for them during a compliance check, to deal with all aspects of that check.


Before we can deal directly with a tax adviser, for example an accountant or agent, valid and specific authorisation needs to be in place. This allows compliance officers to deal with the adviser in respect of the taxes covered by the authorisation.

Customers can currently authorise an adviser (either via HMRC Online Services, form 64-8, or for CITEX a letter of authority for the agent to act) to deal with HMRC for their day-to-day matters.


Where we already hold a formal agent authorisation that covers all areas that are being checked, no further authorisation is needed. However, if the existing authorisation does not cover all the matters we are checking, then further authorisation will be needed.

When a form Comp1 can be used

The Comp1 relates only to the appointment of an adviser to deal with a compliance check. It does not authorise us to deal with that adviser for anything outside that check. The Comp1 also does not replace or amend any existing authorisation made using a 64-8 the online authorisation facility, or in CITEX cases a letter giving authority for the agent to act.

The temporary authorisation can be used to:

  • Extend an existing authorisation, for example where there is already an authorised adviser acting in relation to one head of duty, and the customer now wants the adviser to act on their behalf in relation to additional heads of duty for the purpose of the compliance check
  • Appoint a ‘specialist’ tax adviser to deal with a compliance check, for example in Specialist Investigation cases. This will allow the existing adviser to continue to act for the customer in their day-to-day tax matters.
  • Appoint an adviser to deal solely with the compliance check where there is no existing adviser authorisation

Where the customer wants to cancel the temporary authorisation that they have made on a Comp1, they can do so verbally. Where possible you should also obtain written confirmation, although this is not essential.

Where the customer wishes to change the temporary authorisation, they have made on a Comp1, they will need to submit a new Comp1.

Guidance and access

Unlike a 64-8, a Comp1 cannot be submitted online.

If the customer has already consented to communicating with us by email, they can send the completed Comp1 directly to the compliance caseworker dealing with their check. Remind the customer that personal, sensitive information provided on the form should be encrypted or redacted. Where the Comp1 has been sent by email it must be dated on the form. However, the customer does not need to sign the Comp1 if the email has been sent by the customer. If you have any doubt about accepting the Comp1, you should contact the customer to confirm it.

Where the customer has not consented to using email, they must download and complete the Comp1 and send the paper copy to HMRC.

The Comp1 is available on the Tax agents and advisers pages (Gov.UK Website). Staff can also print a blank copy of the Comp1 from SEES Forms and Letters.

As an alternative to completing a Comp1, the customer can temporarily authorise an agent using a letter or by email, as long as they have already consented to communicating with us by email. The correspondence must contain the same information as is included in the Comp1.

Customers should discuss with their adviser whether the form is appropriate to use. For further information see Tax adviser authorisation for compliance checks ( Website).

An agent can forward customers authority via email but you must be satisfied that this has originated from the customer. You must ensure that the details provided on the COMP1 match those held by HMRC. If you have any doubt you can contact the customer to confirm this.

Extending the compliance check

The temporary authorisation includes provision for extending the compliance check. It automatically covers any additional taxes/duties and periods where we have extended the scope of the original check, for example, to cover earlier/later years.

The Comp1 notes contain information for the customer which advises that they will need to let us know, in writing, if they do not want the temporary authorisation extending.

The authorisation given on the Comp1 will end when the compliance check has been closed and any related appeals have been resolved. If a taxpayer wishes to temporarily authorise an advisor to deal with a complaint related to a compliance check, they will need to provide a separate Comp1.

Action on receipt of form Comp1

Unlike the 64-8, a record of the Comp1 is not held on any ‘main’ HMRC computer system, such as SA, COTAX, VAT Mainframe, or ETMP. Therefore, you must not send the Comp1 to the Central Agent Authorisation Team (CAAT). This is to ensure that there is no confusion between permanent advisers and temporary advisers.

Caseflow Scanning Cases

Caseworkers do not need to see or retain the paper copy of Comp1 in cases where it has been scanned into Caseflow by the HMRC scanning centre.

If you receive a paper copy of the Comp1 and it has not been scanned, you should retain it with the compliance check papers and update caseflow to record that the agent is authorised for correspondence.

The Comp1 should be disposed of at the same time as the compliance check papers.

Non - Caseflow Scanning cases

In EF cases, you should upload or scan the Comp1 to EF as document type MEMO and description Comp1.

Cross Tax Cases

If a temporary adviser is appointed during a cross tax compliance check, the lead caseworker must inform the other caseworkers involved in the check that there is a temporary adviser and the extent of their involvement with the compliance check.

Customer Who Signed the Comp1 Becomes Unable To Deal With Their Tax Affairs

{#IDAWDYRE}If a customer’s health or personal circumstances make it difficult to manage their tax affairs, HMRC must make reasonable adjustments. In rare cases a third party may explain that, even if reasonable adjustments are made, the customer would still be unable to deal with their tax affairs, this isn’t limited to customers with mental impairments.

If we become aware that the customer who signed the 64-8 or Comp1 has become mentally incapacitated and unable to deal with their tax affairs, we can no longer deal with the appointed agent or disclose information on behalf of that customer. In such circumstances we can only deal with:

  • a person who has an Enduring or Lasting Power of Attorney which authorises them to deal with the customer’s property or financial affairs
  • a deputy appointed by the court of protection to do similar (see IDG30432)
  • the equivalent in Scotland and Northern Ireland.

It will then be for the attorney or deputy to decide whether to appoint an agent to act on their behalf with HMRC.


Reasonable adjustments are not limited to customers with disabilities.

Data Security

Caseworkers must be vigilant in ensuring that data security guidance is adhered to. This is especially important where there is the possibility of more than one adviser acting on behalf of the customer, for example, a permanent 64-8 is already in place and a Comp1 is received for a different adviser to deal with the compliance check.

Caseworkers should ensure that they only disclose the information each agent is authorised to see.