Refunds for provisional tax collection when declared provisions lapse ensure repayment of duties inconsistent with final enactments. Where duties were collected under a declared provision that is later enacted in amended form within the early period after a Bill's introduction, refunds must be made of duties that would not have been collected had the enacted provision been the declared provision, subject to a cap equal to the difference between the declared provision's proposed duty rate and the rate in force when the Bill was introduced; similarly, if a declaration ceases to have effect on statutorily specified grounds, duties collected but not chargeable absent the declaration must be refunded.