IHTM04103 | Settled property: charges on temporary charitable trusts
From HM Revenue & Customs · Inheritance Tax Manual
Settled property which for a limited period, however defined, can be applied only for charitable purposes is excluded from the ten-yearly and proportionate charges.
But tax is charged when
property ceases to be held for charitable purposes, or
the trustees make a disposition () which reduces the value of the property so held, .
Any application of the property for charitable purposes does not give rise to a charge.