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HMRC internal manual

Inheritance Tax Manual

Relevant property: inheritance tax deductions

You can allow deduction for any unpaid inheritance tax and interest outstanding at the date of valuation on earlier chargeable events, as long as the payment is to be made from the trust funds. This position is the same as for death estates. (IHTM28170)

When calculating the historic value of relevant property for a proportionate exit charge before the first ten year anniversary, you can deduct any inheritance tax paid by the trust on the set-up or addition.