Since 1997, Statistics Netherlands has collected data on the average house value in the Netherlands based on the Act on Property Assessment (WOZ). This act was introduced on 1 January 1995 and obliges municipalities to assess the value of all property (WOZ objects), within the municipal borders on a regular basis. The WOZ value is used to impose tax on property owners.
So far, the reference dates after 1 January 1995 were: 1 January 1999, 1 January 2003, 1 January 2005 and 1 January 2007. The WOZ values with reference date 1 January 2007 are still preliminary.