STAMP DUTY

A Government tax on the sale of real estate, calculated according to the sale value. It is a tax on specified classes of documents. The classes most common to real estate are:
Stamp duty must be paid before a contract is legal. For example, a court will not recognise a contract on the sale of a house unless stamp duty is paid.

Stamp duty calculator on the sale or transfer of land:

see

www.nsw.osr.nsw.gov.au/taxes/transfer_land/calculator/