The merger of several construction companies in the form of a working group (ARGE) has become a common practice in the realization of individual infrastructure projects and other large projects in the construction industry. Although the reasons for forming an ARGE can be diverse, this corporate cooperation is always a project-related alliance. This characteristic of an ARGE gives rise to a number of corporate and tax law issues. Over the decades, a common ARGE practice has developed to address these problems, resulting in a 'sui generis' legal form. The aim of the study is to outline the essential features of the legal structure of an ARGE and its taxation, and to subject it to critical analysis.