Step 1:
Go to: https://www.altinn.no/en/

Step 2:
Log in with your D-number or Personal Identification Number via MinID or BankID

Step 3:
Click on “Inbox”  then scroll down to, “skattetrekksmelding” or "bekreftelse på D-nummer"

Step 4:
Open the “Document” ➡️ Download this to a PDF-file

Step 5:
English: Upload a copy of the document to the Tax Card section in the app

Helpful link: https://help.staffers.no/en/articles/3349611-passport-and-tax-card