An important episode in the previous century was the fall of the communist economies in Central and Eastern Europe and the Baltic states. The collapse of these economies led to the emergence of so-called countries in transition, which were characterized by rapid economic and institutional change. This transformation has been accompanied by the emergence of a substantial amount of undeclared work, being described as income from productive economic activities that are legal and taxable, but for which do not pay income tax, social security contributions, value-added tax, etc., because they are not reported to the tax, social security, or customs authorities. The research includes notions about taxation in Romania, the economic framework of taxes, fees, and contributions, as well as their management procedures from an accounting point of view. In this research, we analyzed the tax system in Romania in terms of defining, delimiting taxes and fees and organizing and operating the tax system at the national level. At the same time, the main taxes, and duties due by the Romanian economic entities and the related conclusions were presented.