To allow the Belgian administration to identify possible property income earned by an owner-landlord, all residences are listed on the land register known as cadastre.
The fiscal authorities thus determine for each property a cadastral income, the equivalent of the average annual income of a building over a given period of time. It is a theoretical income figure. For example, for a property rented as a residence, the owner declares a cadastral income and the authorities deduct 40 %. The cadastral income, in the absence of a universal realignment, has been indexed since 1991, that is, every year it is multiplied by the index rate of that year. This is the cadastral income which is the basis for payment of the property tax known as « précompte immobilier ». The latter is shared between the region, the province and the commune. Property reductions are applied according to the different regions. For information purposes, the rate in 2017 is 1,7491.