Buyer Stamp Duty (BSD):
You are required to pay BSD for documents executed for the sale and purchase of property located in Singapore. BSD will be computed on the purchase price as stated in the document to be stamped or market value of the property (whichever is the higher amount).
When you buy any property, you need to pay Stamp Duty within 14 days of the date of Contract/Agreement. In most instances, your lawyer acting on your behalf in purchasing the property will arrange for payment of Stamp Duty.
Details can be found here - View It
BSD/ ABSD/ Loan to Value/ Payment Scheme