The rate at which tax is charged under section 65 above on an occasion preceding the first ten-year anniversary after the settlement's commencement shall be the appropriate fraction of the effective rate at which tax would be charged on the value transferred by a chargeable transfer of the description specified in subsection (4) below (but subject to subsection (6) below).
For the purposes of this section the appropriate fraction is three tenths multiplied by so many fortieths as there are complete successive quarters in the period beginning with the day on which the settlement commenced and ending with the day before the occasion of the charge, but subject to subsection (3) below.
Where the whole or part of the amount on which tax is charged is attributable to property which was not relevant property, or was not comprised in the settlement, throughout the period referred to in subsection (2) above, then in determining the appropriate fraction in relation to that amount or part—
The chargeable transfer postulated in subsection (1) above is one—
The amount referred to in subsection (4)(a) above is equal to the aggregate of—
whether or not the property has remained relevant property comprised in the settlement;
Where the settlement commenced before 27th March 1974, subsection (1) above shall have effect with the substitution of a reference to three tenths for the reference to the appropriate fraction; and in relation to such a settlement the chargeable transfer postulated in that subsection is one—