Citizens of non-EU/EEA countries staying in Norway for 3 to 12 months may apply for voluntary membership in the Norwegian National Insurance Scheme (NNHS) upon arrival in Norway.
Fill out the form Application for voluntary membership in the NNHS during stay in Norway - NAV 02-07.05 (nav.no) and return it to your local social security office (nav.no) (Norwegian).
Whether you will be granted coverage depends on whether your country has a social security agreement with Norway and the nature of your residence permit.
Generally, if you are unable to obtain health insurance from your home country, you will be granted coverage in Norway.
Note: Membership in the NNHS may be restricted to urgent care coverage.