The 2001 Population and Housing Census was the last census in which people have to fill out the form themselves. One of the objectives of the census was to improve the quality of the registers so that Statistics Norway can subsequently withdraw statistics directly.

The population register contains information about persons and families, while the Ground Property, Address and Building Register (GAB Register) contains information about homes. Until now, the GAB Register has not been complete because it has lacked information about dwellings in apartment buildings built before 1983.

To upgrade the GAB Register, all dwellings in Norway has been assigned a unique address. Before this, only detached homes and row houses had a unique address, while, for instance, all apartments in the same apartment building had the same address. In the autumn of 2001 all dwellings that did not already have a unique address received an address label on which the dwellings correct address was written. This label was to be affixed to the inside of the entrance door frame.

The new address consists of the old familiar address plus five numbers/letters. For example, the new address for Blåklokkeveien 13C might be Blåklokkeveien 13C H0201, with H standing for main floor, 02 for second floor and 01 for the first dwelling to the left. This address is the correct address of the dwelling when dealing with public authorities and for real estate transaction purposes. People will otherwise continue to use the old address for sending mail.

Denmark and Finland went through the same process many years ago.