If you're separated or not married, the father can declare paternity during the pregnancy, in connection with the birth, or after the birth. 

The Tax Administration receives and processes paternity declarations.

Declaring paternity online

You can declare paternity online on NAV’s (Norwegian Labour and Welfare Administration) website.

You can declare paternity online if

• both parents have a Norwegian national identity number
• both parents are over the age of 18
• the child is born in Norway

You can declare paternity online here

Declaring paternity in person

The father may declare paternity at the following locations:

• At the tax office. Remember to book an appointment.
• At NAV or the office of a justice
• At the midwife’s or doctor’s office in connection with a prenatal check-up, or in connection with birth. It is not possible to declare paternity with a midwife or doctor after the birth of the child.
• At a posted foreign service official’s location, if the father is abroad

Remember to bring valid identification to your appointment.

If the person who has declared paternity is not stated as the father in the birth notification, the mother must approve the paternity.