In case you are not aware (and I cannot locate any update at all on this) HMRC have changed the forms for IHT Accounts, seemingly amalgamating the previous event forms with the main IHT100 form.
There also appear to have been some subtle changes to the guidance on when accounts are or are not required.
Frustratingly, there is no comment on when they will cease to accept the previous IHT100 accounts - I cannot be the only advisor with accounts out for signature on forms that are no longer current?
As an update (as this post was originally submitted on 13 August!) there is more of an explanation in the HMRC Trust and Estate newsletter including to confirm the previous versions of IHT Accounts will be accepted until 31 December 2024.
It is worth being aware that the new IHT100d seems to have a few minor bugs.
Months< 10 may not appear properly in box A7
F10 may produce excessive decimal points
The date entry method in C2, C3 and A7 are not consistent (perhaps intended)
A3 and B6 interact/overwrite entries of the first trustee names and capacity on page 11, and vice versa
I flagged these with Helen Thornley for ATT/CIOT to take up with HMRC