Plus Valia is a local tax calculated as a percentage of the difference in the increased value of the property from when it was last sold. The calculation is based on the rateable value, not the real value of the property and is a one time payment charged when a property changes hands. Each town hall defines the percentage and it varies according to municipality. Not all town halls enforce Plus Valia; although legally it is the responsibility of the vendor, it used to be customary for the purchaser to pay the tax. However, it is now becoming increasingly common for responsibility of the tax to lie with the vendor.