The article concerns the new regulation of commercial law relevant to a group of companies. It analyses the regulation defining the creation of a group of companies and selected matters related to its functioning. A part of the article is dedicated to the issue of issuing binding instructions to a subsidiary company and the acceptable responses of the management board of this company to a particular instruction. Among other things, it is confirmed that the Code of Commercial Partnerships and Companies does not impose on the management board of the subsidiary company the duty to execute binding instruction. Lack of definitions of crucial terms relating to groups of companies, for example, interests of a group of companies, handicaps the application of the new regulations.