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HMRC internal manual

Debt Management and Banking Manual

Customer contact and data security: contact with third parties: how to handle correspondence from third parties: confirming there is valid authority for tax credit cases

Tax credits and written third party authority

Before you deal with a third party tax credit case you need to ensure that the authority you hold is valid and the correct form has been completed. There are three categories of third party and each requires a different form of authorisation.


Voluntary organisations (for example, the Citizens Advice Bureau (CAB)) or individuals (for example, a friend or neighbour) require form TC689 or an equivalent containing the same information.

The authority to act is only valid for 12 months from the date of signature (which must be original). In joint claims the authority should be signed by both claimants.

Debt management companies for whom the claimant is paying a fee should be treated as an agent and should complete a 64-8. It is not acceptable for a paid professional to complete a TC689 or their own equivalent document. The signature must be original. In joint claims the authority should be signed by both claimants.


If the customer cannot control their own affairs, someone is appointed to act on their behalf; this could be due to illness, disability or mental health.

They can be appointed by:

  • a court of law
  • the Department for Work and Pensions (DWP)
  • the Department for Social Development (DSD) in Northern Ireland
  • HM Revenue & Customs (HMRC).

The original document of appointment or proof of appointment must be supplied and should be returned to the appointee once the records have been updated.

Details of the third party authority should be recorded on IDMS Notes and Assets (as a permanent note) and all available head of duty system records.