14Vehicles (excise): charge for new licence under s. 13 of Act of 1949
(1)The following provisions shall have effect where under subsection (1) of section thirteen of the Vehicles (Excise) Act, 1949 (which imposes a higher rate of duty in certain circumstances where the condition of a vehicle or the use made of it is altered while a licence under that Act is in force in respect of the vehicle), an existing licence is exchanged for a new licence, and the date on which the higher rate of duty becomes chargeable falls after the end of September, nineteen hundred and sixty.
(2)The payment to be made on the exchange shall, instead of being of the amount specified in that subsection, be equal to the appropriate proportion of the difference between—
(a)the amount payable under that Act on the original licence, and
(b)the amount payable under that Act on a licence taken out for the period for which the original licence was issued but at the higher rate of duty, that amount being calculated, if that rate has been changed since the issue of the original licence, as if that rate had been in force at all material times at the level at which it is in force when it becomes chargeable.
(3)For the purposes of this section the appropriate proportion is the proportion which the number of months in the period beginning when the higher rate of duty becomes chargeable and ending with the end of the period for which the original licence was issued bears to the number of months in the whole of the last-mentioned period, any incomplete month being treated as a whole month.