Hey Simon and thanks so much for a super question! Lots of potential flags in there. I assume that you are one of the executors appointed by the Will of the deceased, and in the process of applying for Probate? So, here goes with the basic principles!

The starting point of course to establish an Inheritance Tax (IHT) liability is to look at the estate as a whole (not all assets will pass via the residuary clause of the will). So, one would expect to look at things like lifetime gifts; joint assets; and assets to which the deceased might have had some form of trust interest (eg an Interest in Possession Trust).

Next you mention legacies. There are rules around where and how IHT against legacies is paid from (either against the legacy itself, or taken from residuary estate). So this will be something to explore and will be defined by the will/law.

There is an alarm bell in there that the spouse is only to receive 10%? This seems extremely unusual and I wonder if there are grounds for them to dispute the will if it leaves them in financial difficulties?

Next, are there any assets which might mitigate IHT due to relief that they attract? For example are there business assets, or is there a matrimonial home?

As to the tax attributable to the residue itself, then one would also (in addition to the above) want to look at things like are other residuary beneficiaries exempt (eg charities). The spouse is of course exempt (spouse exemption) and amounts passing to a surviving spouse on death (whether via the will or otherwise) are exempt from IHT.

A really super question Simon for which a big thank you. We can obviously only discuss the generic subject matters that your query points to, but if you would like our specific advice/help then do please reach out directly.

Best wishes from Team QLAW!