The property comprising the chargeable transfer (value now chargeable) is the value of the ‘loss to the settlement’. That is the amount by which the value of the relevant property in the settlement is less immediately after the event than it was before. ( IHTM42119)
The rate to apply to the transfer depends on whether the
transfer is before or after the first TYA.
Once you have found the effective rate, the calculation is
then reduced by a number of 40ths, to take into account the length
of time in quarter years that the property has been in the trust
since set-up or the last TYA.