IHTM09381 | Obtaining mandates: introduction
From HM Revenue & Customs · Inheritance Tax Manual
If possible, you should obtain a mandate from the taxpayer under enquiry before contacting the third party.
There are two forms of mandate
a mandate which, suitably amended if necessary according to the facts of the case, may be used for other enquiries of third parties (IHTM09383).
If you cannot get a mandate from the taxpayer you should first approach the third party on an informal basis. If you need to consider issuing an information notice (IHTM32191) under FA08/Sch36 to a bank or building society you should consult Litigation before taking any action.
You should make the taxpayer aware that the bank may charge them for the information provided.