IHTM16083 - Settled property exemptions: annual exemptions
The annual exemption applies on the lifetime termination of a qualifying interest (IHTM16162) in settled property only if the person whose interest is terminated gives notice in writing to the trustees of the settlement within six months of the termination specifying how much of the annual exemption is available [to him as an individual] that can be used against the termination (IHTA84/S57 (3) and (4).
The notice should not be sent to HMRC Inheritance Tax. It should be retained by the trustees in case it is subsequently required by HMRC Inheritance Tax.