If A and B are married, and A subsequently dies, leaving their estate in full to B (and A passes an unused NRB);
And B then marries C, and B leaves by Will their entire estate (which includes B’s unused own full NRB) to C;
And then B dies;
Can C (as i.e. executor and sole beneficiary) by a Deed of Variation redirect an amount up to the NRB to a discretionary trust - and thereby ‘save’ the additional (A’s) NRB? So that on C’s death, he/she will still have two NRBs (i.e. B’s and C’s)?
Use of IHTA 1984 s142. would allow the redirection to which you refer.
Once there has been a TNRB this merges with the NRB to form a new NRB. On the execution by C of a redirection (under s142) of, say, £325k of C’s inheritance from B on DT then B’s unused double NRB (ie including the TNRB from A) would reduce to a single £325k NRB available for C’s PRs to claim.
The only difference between a NRB and TNRB is that the latter cannot be used against any lifetime CLT in calculating the IHT thereon.