70Chargeable amounts
(1)This section has effect to determine the chargeable amount for the purposes of section 68 above.
(2)If the chargeable event falls within section 69(1)(a), (b) or (c) above the following rules shall apply—
(a)if the event constitutes a disposal of the securities by the trustees for the purposes of the Capital Gains Tax Act 1979, the chargeable amount is an amount equal to the sums allowable under section 32(1)(a) and (b) of that Act;
(b)if the event does not constitute such a disposal, the chargeable amount is an amount equal to the sums which would be so allowable had the trustees made a disposal of the securities for the purposes of that Act at the time the chargeable event occurs.
(3)If the chargeable event falls within section 69(1)(d) above the chargeable amount is an amount equal to the sum concerned.