IHTM31756 | Assessing: deposits: money attributed to the wrong file
From HM Revenue & Customs · Inheritance Tax Manual
You must check all payments received at your file to make sure they have been allocated to the right file. If you think that a payment does not belong at your file refer this to Accounts Nottingham.
Do not use a Sect 6 (IHTM31641) to transfer the money.