STAMP DUTY IS PAYABLE ON THE PURCHASE OF A PROPERTY ...

and is payable to the New South Wales Treasury's Office of State Revenue. Stamp duty is also payable on a mortgage.

Full information, including a stamp duty calculator, is on the Office Of State Revenue's website:

http://www.osr.nsw.gov.au/portal/page?_pageid=33,63559&_dad=portal&_schema=OSRPTLT