Where, having hired (otherwise than by means of hire-purchase) a vehicle to which this Part applies, a person subsequently becomes the owner of the vehicle, then, for the purposes of the Tax Acts (and in particular sections 380L and 380M) -
(a) so much of the aggregate of the payments for the hire of the vehicle and of any payment for the acquisition of the vehicle as does not exceed the retail price of the vehicle at the time it was made shall be treated as capital expenditure incurred on the provision of the vehicle, and as having been incurred when the hiring began, and
(b) the payments to be treated as expenditure on the hiring of the vehicle shall be rateably reduced so as to amount in the aggregate to the balance.