Tax management can be described as a set of activities that lead to the optimization of the tax liability of the taxpayer. The aim of this paper was to identify the key factors that most influence the optimization of company´s tax liability. The conclusions of the research allow defining the main factors and at the same time highlighted the possibility of their division into three main areas, namely: need of tax liability management, professionalism of the people responsible for company´s tax planning and cooperation with external tax professionals. The key factors, including their impact on the company´s tax liability, are further discussed from many aspects.