In 1796 tax became payable on legacies and residues of personal estates upon death. The Death Duty as it was called began as a tax on particular legacies however it was extended such that in 1811 all estates passing through the probate court (the mechanism by which wills were executed) were included.
Abstracts of the Death Duty records can now be found at teh PRO and cover the period of 1786-1903.
Death duty registers can help the family historian in the number of ways. Firstly, it can be used to find the court in which a Will was administered. Secondly, it can help the family historian discover the value of their ancestors estate and what happened to it (which will not be covered in the Will itself).
Records can be found at the PRO Chancery Lane in IR 26 – Board of Inland Revenue Records