This article deals with the interpretation of the concept branch of activity. This concept is of significant importance for tax relief by the two methods of restructuring a company called transfer of assets (Sw: verksamhetsavyttring) and under-price transaction (Sw: underprisöverlåtelse). The ECJ has in a recent case defined the concept branch of activity relating to the EC harmonised transfers of assets. The main question in this article is whether the EC case law on transfers of assets has to be applied to the national phenomenon under-price transactions. The conclusion of the article is that it probably has to, not due to EC Law but because of the principles of interpretation in national law as well as the principle of equal treatment in the Swedish Constitution.