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Setting up a company
In order to work as an artist, with the ability to invoice clients, you need to register in Brønnøysundregisteret to get an organization number as a sole proprietorship (enkeltmannsforetak) or shareholding company. Most artists in Norway are registered as a sole proprietorship – unless they have a studio with employees or a big production.
As an artist you are self-employed. Often artists have a mixed economy with some income from job assignments related to art, jobs not related to art, grants and support, sale of works, commission work, and so on.
Before you can begin the process towards a sole proprietorship, you need to have a personal number or D-number, and an electronic ID.
You’ll find the needed information on how to obtain a personal number or D-number here: https://www.skatteetaten.no/en/person/foreign/norwegian-identification-number/
You’ll find the needed information on how to obtain an electronic ID: http://eid.difi.no/en/id-porten/how-obtain-electronic-id
When you have all the aforementioned personal information in hand you can register at Brønnøysundregisteret. Once completed you’ll receive an organization number and be registered in the tax-register. You can register here: https://www.brreg.no/business/sole-proprietorship/registration-of-a-sole-proprietorship/
Remember to define your business as producing art, and it might be a good idea to also include artistic assignments, giving workshops, etc.
For more advice on how to proceed with the process, you’ll also find a rather useful guide (in English) on how to start and register a business in Norway on Altinn: https://www.altinn.no/en/start-and-run-business/ and how to register a sole proprietorship here: https://www.altinn.no/en/start-and-run-business/planning-starting/registration-of-the-enterprise/starting-and-registering-a-sole-proprietorship/