Ad valorem from latin: “According to value”. This is a phrase is used in reference of the method for levying duties (i.e. tax) on a transaction or property, which is payable based proportionally on the value of the transaction or property, rather than on its quantity.
The most prevalent example of the calculation of duty on an ad valorem basis is the transfer of land or business duty (formerly known as stamp duty in NSW). The duty on a sale or transfer of land is paid in accordance with the rates published by Revenue NSW. According to the value of the purchased or transferred land, vendors will have to pay an amount upfront plus a percentage of every $100 of the value of the land that exceeds a nominated threshold.
“According to the value”. The phrase is used of duties levied according to the value of the subject matter. It is commonly applied the value of property as stamp duty, but can also be a tax on personal property, such as a motor vehicle tax.