128Alteration of contracts if cost of supplying etc. assessable goods is affected by later alteration to sales tax law

128 Alteration of contracts if cost of supplying etc. assessable goods is affected by later alteration to sales tax law

(1) If, after a contract involving assessable goods has been made, an alteration to the sales tax law happens and the alteration directly causes an increase or decrease in the cost to a party to the agreement of complying with the agreement, then the contract is altered as follows: (a) if the cost is increased—by allowing the party to add the increase to the contract price; (b) if the cost is decreased—by allowing the other party to deduct the decrease from the contract price. (2) The contract is not altered if: (a) the contract has express written provision to the contrary; or (b) it is clear from the terms of the contract that the alteration of the sales tax law has been taken into account in the agreed contract price.