I live in Portugal and own a Norwegian AS — where does the company pay tax?

The company follows its management, not your address — but if you are the management and you now decide everything from Portugal, the company's tax home can quietly migrate with you. The defense is substance: a Norwegian board reality, documented decision-making in Norway, your role defined honestly. This is the most common second-order surprise in relocations: people plan their own taxes and forget the company has a residency too.