IHTM30552 | Erroneous or excessive repayments of tax: repayment of deposits
From HM Revenue & Customs · Inheritance Tax Manual
The repayment of money on deposit () is not regarded as a repayment of tax for the purpose of these instructions. But if the money on deposit came from a repayment of tax, these instructions () apply to the repayment of tax to the extent to which it was excessive.