Persons residing in Norway are obliged to report change of address to the Norwegian authorities. If you are staying outside of Norway or a Nordic country for at least six months, you must report the change of residence and new address.
You must fill out a form from the Norwegian Tax Administration and send it to the tax office at your place of residence in Norway. You must report the move no more than 31 days before your departure. Please see Moving from Norway - The Norwegian Tax Administration