Where can I check my Tax in Norway?

For tax changes, complaints and more, skatteetaten.no . For tax reports, applications related to tax, you can visit altinn.no .
Altinn is the goverments online service, where you can access many services such as: Taxes, company tasks, applications and much more.
To access Altinn, you will need to identify yourself online and will need a d-number or person number.

Altinn about self:

Altinn is developed, operated and managed by the Altinn co-operation, that consists of multiple government bodies. The Brønnøysund Register Center manages the technical solution on behalf of the co-operation, and decides how it should be developed.

Today Altinn is a well established and comprehensive platform, and shows great growth both in data volumes, number of connected government bodies and number of digital services. It is constantly being developed with both improvements of current and introduction of new functionality. This functionality is described more in-depth (in Norwegian) in Altinnett.

Altinn also has a lot of useful information for those who wish to establish and run businesses in Norway, shown under Start and run business. These pages also contain a list of business support schemes.