A significant portion of the municipal income in Turkey comes from property tax. However, the process of registering property and associating it with owners presents significant problems in the calculation and collection of this tax. In the study reported in this paper, a spatial address registration system based on street addresses and using a geographical information system was developed to reduce property-tax evasion. The model was applied on a 1600 ha area that included 10 059 independent households and 7013 land parcels. The annual tax-evasion loss due to non-declaration in the study area was determined. Based on a national total of 20 million households and 57 million land parcels, the study showed that the country's annual property-tax loss was around 2.9 billion Turkish Lira (0.6 pound billion). The proposed model provides an effective solution to minimise this loss.