It is common nowadays for individual consumers to buy goods from overseas via their friends or internet websites such as Amazon. Therefore it is important for you to know that your purchases is also subject to GST when you import the goods into Singapore, whether through ordinary mail or courier.
The GST amount that you have to pay to Customs is computed based on the CIF value (cost, insurance and freight) of the goods plus all duties payable.
However, GST need not be paid for goods (except for dutiable products) with CIF value of not more than $400. Where the CIF value is more than $400, the entire sum will be subject to GST.