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HMRC internal manual

Inheritance Tax Manual

Assessing: calculation principles: apportioning the tax charge

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 (IHTM31012) at each Entry (IHTM31011).


Theresa held personal assets and freehold property (on which the instalment option is claimed), and also had a qualifying interest in possession (IHTM16061) 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