You can appeal against your tax assessment for the 2015 income year or earlier
You are entitled to appeal against your tax assessment. Appeals must be submitted within no more than six weeks after you receive your tax assessment. You will find this date in the top right of your tax assessment.
Your appeal must explain why you believe the tax assessment is wrong.
If you believe the error is that not all tax deductions or advance tax have been included, you must appeal to the tax collector in your local municipality.
The Norwegian Tax Administration’s service declarations (in Norwegian) tell you what service you can expect from the Administration. You will also find information on who to contact and what your rights and obligations are.