IHTM35172 | Compliance with a testator's request: what you should do if you are notified of a transfer
From HM Revenue & Customs · Inheritance Tax Manual
You should satisfy yourself that the transfer meets the requirements (IHTM35171) to fall within IHTA84/S143. Where it does the IHT implications are that
the IHTA84 applies, and so tax is charged or exemption given as if the property transferred had been bequeathed by the testator’s will to the transferee, and
the transfer is not a transfer of value, IHTA84/S17(b).