You can apply to change your tax deduction card by filling in the form named RF-1102 "Application for new or changed tax card/advance tax." and enter information on how much you expect to earn this year.
Online users can change/amend tax deduction card online at skatteetaten.no.
Exemption from National Insurance contributions
If you are an EU/EEA citizen and wish to be granted exemption from National Insurance contributions, you must apply for this exemption to nav.no.