IHTM31013 | Assessing: calculation principles: apportioning the tax charge
From HM Revenue & Customs · Inheritance Tax Manual
To work out the correct amount of tax to pay on a chargeable occasion you will prepare a calculation, or several calculations.
The calculation of tax may be broken down into several parts. You will need to prepare a separate calculation for each different assessment group () at each Entry ().
Example
Theresa held personal assets and freehold property (on which the instalment option is claimed), and also had a qualifying interest in possession () entitlement in a Will Trust (containing listed shares only) when she died.
You will need to raise separate calculations for the:
Free estate NIOP
Free estate IOP, and
Will trust NIOP