Where any new F1customs duty or new excise duty is imposed, or where any F1customs duty or excise duty is increased, and any goods in respect of which the duty is payable are delivered after the day on which the new or increased duty takes effect in pursuance of a contract made before that day, the seller of the goods may, in the absence of agreement to the contrary, recover, as an addition to the contract price, a sum equal to any amount paid by him in respect of the goods on account of the new duty or the increase of duty, as the case may be.

Where any F1customs duty or excise duty is repealed or decreased, and any goods affected by the duty are delivered after the day on which the duty ceases or the decrease in the duty takes effect in pursuance of a contract made before that day, the purchaser of the goods, in the absence of agreement to the contrary, may, if the seller of the goods has had in respect of those goods the benefit of the repeal or decrease of the duty, deduct from the contract price a sum equal to the amount of the duty or decrease of duty, as the case may be.

Where any addition to, or deduction from, the contract price may be made under this section on account of any new or repealed duty, such sum as may be agreed upon or in default of agreement determined by the Commissioners of Customs . . . F2, as representing in the case of a new duty any new expenses incurred, and in the case of a repealed duty any expenses saved, may be included in the addition to or deduction from the contract price, and may be recovered or deducted accordingly.

This section applies whether or not the goods have undergone a process of manufacture or preparation, or have become a part or ingredient of other goods.

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