IHTM14831 | Lifetime transfers: associated operations: gifts with reservation (GWRs)
From HM Revenue & Customs · Inheritance Tax Manual
Where there is a disposal by way of gift, and the donor obtains a benefit through associated operations, treat this as a benefit to the donor ‘by contract or otherwise’ for the purposes of FA86/S102.
This is covered in more depth at the GWR (IHTM14338) section of this manual.