The present diploma thesis is focused on the analysis and the assessment of the state of the art of legal regulations of rights and duties of the persons who participate in the administration of taxes in relation to basic principles of tax administration. The core legal regulation which is relevant for the theme under study is the tax rules that comprise a basic survey of principles applicable by the entities of the administration of taxes in practice. The tax rules is thus a main source of the findings for the enforcement of individual as well as partial rights and duties by tax payers and third persons that participate in the administration of taxes, and at the same time it determines the scope of the powers of the administrator of the ta...