This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

Inheritance Tax Manual

Structure of the charge: what makes up a person's estate?

The value transferred by a transfer of value (IHTM04024) is quantified by reference to a person’s estate. This is so whether you are dealing with a lifetime transfer (IHTM04051) or the deemed transfer on death. (IHTM04041)

The word ‘estate’ is given its general meaning and includes all property (IHTM04030) to which the transferor is beneficially entitled, (IHTM04031) IHTA84/S5(1). The legislation then goes on to both extend (IHTM04032) and restrict (IHTM04033) the meaning of the word.