What is BAG?

The BAG (Basisregistratie Adressen en Gebouwen — Key Register of Addresses and Buildings) is the Dutch national register of all addresses and buildings. Each address has a unique ID; buildings and units are linked with geometry and attributes such as year built and use type.

The BAG is maintained by municipalities and distributed nationally via PDOK (Location Server, WFS) and the Nationaal Georegister. Essential for geocoding, crisis management, taxation, utilities, and nearly every map application in the Netherlands.

The BAG is not a topographic map (that is BGT/BRT) or cadastral ownership register (BRK). It is often the first source for where people live or work and which building stands at a location.