The issue is whether the "joint" account holder is claiming the money in the accounts. Or whether there is an acceptance that the monies are for the estate.
In answer:
"are the entire sums in the joint account at death deemed part of the estate as the deceased funded the entire account"
Not necessarily. If the intention by the deceased was to benefit the other joint holder, then no.
See Part 6 of the CA 24
[broken link removed]ca24.pdf
"if so are the entire sums in both account subject to CAT"
If the funds are part of the estate, then yes.
"does the CAT liability fall to the named beneficiary in the will - i.e. 33% must be paid in tax -
even though the account might be assumed to transfer to the third party joint account holder who is not named in the will?"
As above
"Can the beneficiary therefore really be asked to pay CAT on funds they cant' access and can the third party be made to pay the funds over to me in the account (less any funeral expenses) to pass to the named beneficiary in line with the intentions of the will - I presume not?"
You're the executor - you have to work this out. You should be thinking in terms of securing the funds to prevent them being withdrawn. You can write to the bank and confirm that your understanding is that the funds belong to the estate.
"Both parties are family members - so I don't want to create issues. But I just need to know what the tax and probate position is - and whether I can use the funds in the account to meet sums due on the estate (legal, probate fees etc) without being out of pocket before passing the sums to the beneficiary."
If the funds belong to the estate, not the named joint account holder, the funds can be frozen by notifying the bank.
In terms of whether the funds , if belonging to the estate, can ultimately be used for the payment of expenses, it depends on (a) the wording of the will - do the funds form part of the residue? and (b) whether the estate is solvent?
mf