TAG Colonia-Immobilien AG is a Hamburg-based property company focused on the German residential real estate sector. It is engaged in the acquisition, sale, and management of real estate in Germany. The group's properties are located in various regions of northern and eastern Germany and North Rhine-Westphalia. The company's business model is the long-term letting of flats. It operates in Berlin, Chemnitz, Dresden, Erfurt, Gera, Hamburg, Leipzig, Rhine-Ruhr, Rostock, and Salzgitter.