Stamp duty is calculated based on the current NSW threshold. The time taken to accrue the same dollar amount of stamp duty in property tax is calculated based upon the following: the assumption that the unimproved land value is 60% of the purchase price. The annual tax is calculated based on the NSW property tax proposal of $400 plus 0.3% of the unimproved land value each year, factoring in a 2.5% increase in land value per year.