Every employee must register with the Norwegian Tax Administration (Skatteetaten) as soon as possible upon arrival in Norway.
Registration is done at the nearest Skatteetaten office or Service Centre for Foreign Workers (SUA). Registration requires a valid passport or ID card, a signed employment contract and an address in Norway (this may include a temporary accommodation address). Sometimes you may be asked to provide additional confirmation of employment from your employer.
During registration, an identity check (ID-kontroll) is carried out, during which your identity is confirmed using your passport or ID card.
After this check, the employee is given a D-number, which is a temporary personal identification number used for tax, employment and banking purposes. Once the D-number is received, the Skatteetaten issues a tax card (skattekort), which indicates how much tax is to be deducted from your salary.
The D-number and tax card are usually issued within 1-2 weeks of the date of your visit.
D-number users must apply for a new tax card (skattekort) each year. The card is not issued automatically, so it is recommended to apply for one in December-January so that you start the new year with the correct data.
If the tax card has not yet been issued, your employer must temporarily deduct 50% of your salary in taxes - this is the official rule of Skatteetaten.
To avoid tax arrears, it is recommended that you log in to your Skatteetaten.no account every December-January and check your tax card. This will ensure that your income, workplace and benefits are correct.
Read more here:
https://www.skatteetaten.no/en/person/taxes/tax-deduction-card-and-advance-tax/i-am-a-foreign-employee/