This applies if you:

• Have applied for this citizenship, or
• Have explicitly confirmed that you accept the citizenship, for example where citizenship is acquired by notification

This rule shall apply correspondingly to children under 18 years of age. A child who acquires another citizenship by application or explicit consent shall lose his or her Norwegian citizenship where the parents jointly or the parent who has sole parental responsibility, have or has lodged the application or given the consent. See below on children's loss in the case of automatical acquisition of citizenship as secondary persons

Exemptions

If you are granted a citizenship in another country automatically (not by application or notification, nor having explicitly confirmed that you will become a citizen of another country), you will not lose your Norwegian citizenship.

Children's loss in the case of automatical acquisition of citizenship as secondary persons

This applies if the child under 18 years of age

• is not married or a registered partner; and
• acquires another citizenship because a parent acquires another citizenship.

The child's citizenship is not acquired by application or explicit consent. Whether the child acquires the citizenship automatically is defined in the legislation of the country.
 
A child who is not married or a registered partner, loses automatically the Norwegian citizenship where 

• the parent has parental responsibility; and
• the other parent is not a Norwegian citizen

Children’s loss as secondary persons according to previous laws on citizenship

Untill September 1st  2006 Norwegian citizenship was lost by an unmarried child under 18 years of age who acquired the citizenship of another state because one of its parents acquired citizenship of another state upon application or by express consent or by accepting public service in another state where

• he or she had the custody of the child alone; or
• he or she had the custody together with the other parent and the latter was not a Norwegian citizen.

Until 1 July 1979 an unmarried child under 18 years of age also lost Norwegian citizenship if it acquired foreign citizenship by the fact that the parents married one another, and the child was resident or subsequently moved abroad.