80% of NRB rule HMRC reporting

I am trying to find the rules, legislation, or SI that set out the rules relating to reporting requirements when assets in a discretionary trust go over 80% of the NRB.

I understand the reason HMRC wants to know, as some DTs value will go over the NRB and create an IHT liability.

But where you have a mixed trust and the DT element is capped at the available NRB the DT can never go over the NRB so no IHT charge can be created. Surely those trusts do not need to be reported to HMRC.

Thank you

s.216 IHTA. The exceptions are in The Inheritance Tax (Delivery of Accounts) (Excepted Settlements) Regulations 2008

Re Excepted settlements see SI 2008/606 Reg 4 (as amended).

Malcolm Finney