Abstract: Increasing the quality of management decisions in the field of organisational tax burden evaluation and regulation, first of all, relates to the process of diasnosing the current state thereof, thus the topic of the research is very important. Diagnostics shall mean the evaluation of the current state of an economic entity or organization using both direct and indirect methods. The subject of the research is the methods of evaluation and state regulation of organisational tax burden under the laws of the Russian Federation. In their research the authors have used the methods of analysis and synthesis, evolutionary and systems aproaches, multivariate statistics and simulation modeling. The research is devoted to the development of the concept of organizational tax burden regulation based on economic and mathematical instruments that is aimed at ensuring the balance between fiscal and stimulating functions of taxes based on the prior diagnostics of the current state of tax burden using the diagnostic instruments developed as part of the concept. According to the author, these instruments can increase the quality of control and analytical efforts of the Federal Tax Service.