IHTM14711 | Lifetime transfers: specific lifetime reliefs: gifts with reservation (GWRs): when double charges relief arises
From HM Revenue & Customs · Inheritance Tax Manual
Relief under the Inheritance Tax (Double Charges Relief) Regulations 1987 (SI1987/1130) Reg.5 will apply in instances where a failed potentially exempt transfer (PET) (), or an immediately chargeable transfer (), is also a GWR () and the asset transferred becomes chargeable a second time on the transferor’s death because either
the reservation continued to the date of death so that the asset concerned is treated by as property which the deceased was beneficially entitled to, or
the asset ceased to be subject to a reservation before the death and became a deemed PET () on that date.