Different rules apply for how you should register your move and change of address, depending on where you move to or from, for example whether you move within Norway, within the Nordic countries or to countries outside the Nordic countries.
Moving to Norway
If you are moving to Norway and plan to live here for more than 6 consecutive months, or more permanently, you must report a move to Norway. Notification of moving to Norway requires a personal appearance at your nearest tax office to undergo an ID control. You can book an appointment and read more about how to report a move to Norway here: https://www.skatteetaten.no/en/person/national-registry/moving/to-Norway/
You do not need to report a move if you will be staying in Norway for less than 6 months. However, you must apply for a tax deduction card if you intend to work in Norway. If you are commuting to a country within the EEA area, you may be exempt from the requirement to register your residential address in Norway, provided certain conditions are met.
Moving within Norway
You must send a change of address notification to the National Population Register within 8 days of your move. You may also report your change of address to the National population registry and Posten at the same time on Posten.no.
Moving from Norway to another Nordic country
You need only report your move to the authorities in the Nordic country to which you move (Sweden, Iceland, Finland or Denmark – including the Faeroe Islands and Greenland). Information about moving to the Nordic countries is available on the Norden.org website.
Moving from Norway to a country outside the Nordic countries
You must notify the National Population Register of your move abroad to a country outside the Nordic countries.