Controlling is a relatively young function of management, whose importance in recent times is extremely important for achieving goals, measuring results and the key to making future decisions closely related to the business of companies. Initially, controlling was implemented mainly in the private sector, but the development of information technology and the importance of controlling in private companies, contributed to the expansion of controlling in the public sector. One of the most well-known forms of controlling is IT controlling, which connects controlling, IT and corporate supervision. In the public sector, tax controlling is of special importance. The basis of tax controlling is the tax system. Public institutions (such as the Tax Administration) constantly use and improve the tax system, which consists of all taxes in the country. Of all taxes, income tax, profit tax and value added tax stand out. In the case of established irregularities of taxpayers, the tax authority in accordance with the established violation of tax regulations, may open tax supervision. Tax reform in 2020 brought a number of changes in the tax system, which affected the operations of companies in the public and private sectors.