IHTM22031 | Interest in unadministered estates: statutory provisions

From HM Revenue & Customs · Inheritance Tax Manual

is relevant when a person ("the beneficiary") would have been entitled to the whole or part of the residue of the estate of a deceased person if the administration of that estate had been completed

The effect of is that for IHT purposes the beneficiary's interest whether limited or absolute is treated as a direct interest (and not merely a right) in the assets constituting the unadministered estate.