IHTM35166 - Disclaimers: class-closing rules
It is possible for a disclaimer to be made which, instead of accelerating the subsequent beneficial interests, so that they immediately vest in the remainderman absolutely, causes them to vest subject to defeasance (for example, on the remainderman’s failing to survive the person who disclaimed the prior interest). Any case of this nature should be referred to Technical to ensure consistency of practice not only within HMRC IHT but also between IHT, IHT Policy Group and HMRC Trusts.
Where vesting is postponed in a Scottish trust, you should ask Technical to advise on the subsequent devolution of any disclaimed property.