Since the discount is agreed upon prior to the importation, the price paid or payable is S$180 and is an acceptable basis as Customs value.

A discount will be considered in determining the transaction value of imported goods if the discount is actually taken to reduce the net amount actually paid by the buyer for the imported goods and is agreed on prior to the importation of goods.

Generally, discounts given by suppliers under normal trade practices such as cash, quantity or trade discounts are acceptable deductions and can be excluded for GST computation purposes.

There are some discounts that are not to be excluded for GST computation purposes. They include (but are not limited to) those given due to the following reasons:

1. The buyer and seller are related and the transaction price is affected due to the relationship;

2. The buyer undertakes certain activities for or on behalf of the seller as part of the payment under the contract of sale;

3. The buyer provides other goods/services to a third party for or on behalf of the seller as a condition of sale for the imported goods; and

4. The price of the imported goods has received credits made in respect of earlier transactions.

You may refer to the procedures of establishing Customs Value for imports here.