The starting date of the settlement is defined under IHTA84/S60 as the time when property first became comprised in it (and not as any later time when it first became held on discretionary trusts).
In the case of trusts created by will, IHTA84/S83 provides that the starting date is the date of death.
If a will or intestacy is altered by an IOV to create a trust, the start date is taken back to the date of death. ( IHTM42228)
For the purposes of the ten-yearly charge, the trust’s starting date is never altered. For example, trusts that were previously subject to IHTA/S71 will cease to be so if they do not provide – or are not modified to provide before 6 April 2008 – absolute entitlement at age 18 or 25. The settled property will become relevant property when S71 ceases to apply ( IHTM42087), but the starting date of the settlement does not change.
IHTA84/S80 provides an artificial start date if the settlor or their spouse had a life interest when the trust commenced. However the ten year anniversary date reflects the first start date. ( IHTM42231)