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.