The purpose of the study is to cover the main theoretical aspects related to the concept of a progressive tax scale; to analyse the history of the development of a progressive tax scale; to substantiate expediency of application of a progressive scale of the taxation as the factor of economic stability of the budgetary system of the Republic of Kazakhstan. The study is based on the methodology of scientific knowledge, systematic analysis of the theory of progressive taxation. In addition, the study also used the following leading methods – the method of scientific abstraction, generalisation, comparison, analysis and synthesis, grouping, formalisation, historical and logical analysis of theoretical and practical material. For example, with the help of the method of scientific knowledge, the tendency of development and functioning of a progressive tax scale was studied. Methods of abstraction and generalisation allowed identifying the main aspects that need to be taken into account when introducing a progressive tax scale in the tax system of the Republic of Kazakhstan. The method of comparison helped to compare the practice of other countries in the field of functioning of the progressive tax scale. Using the historical method, the evolution of the formation of a progressive tax scale was revealed. The article presents a detailed analysis of the evolution of the progressive tax scale. Researchers are trying to reveal the meaning of basic concepts and categories, to characterise the progressive tax scale, as well as to justify the necessity of its application for the purpose of economic stability of the budget system of the Republic of Kazakhstan.