The principle of equity in income taxation: a retrospective of economic thought and implementation within the framework of tax reform - 2025.

The subject of the research is the evolution of the principle of equity in income taxation within economic theory and its implementation in Russia as part of the tax reform of 2025. Starting from 2025, a five-tier progressive personal income tax scale has been introduced in Russia. One of the objectives of the tax reform set by the President of Russia was to ensure the fairness of taxation for citizens. At the same time, the tax reform did not resolve a number of issues regarding income taxation that hinder the achievement of equity. The search and scientific justification of answers to these questions determine the relevance of the research. The aim is to assess the completeness and correctness of the implementation of the principle of equity in income taxation within the framework of the tax reform conducted in Russia in 2025, in order to substantiate the possibilities for its improvement based on the study of the evolution of economic thought regarding tax fairness. In the framework of the research, general scientific methods of analysis and synthesis, movement from the abstract to the concrete, dialectics, as well as methods for analyzing the results of sociological surveys and focus groups have been applied. As a result of the research, within the study of the evolution of various theories' views on the fairness of income taxation, it has been determined that the modern understanding of tax fairness is a synthesis of the evolution of economic thought. Discussion questions have been identified, and deformities of equity in income taxation have been highlighted. Based on the analysis of sociological research results, the contemporary perception of personal income tax fairness in Russia has been defined. It has been substantiated that the tax reform of 2025 contributes to increasing the fairness of personal income tax, however, elements exist within the structure of personal income tax that hinder the full realization of the equity principle. These include, in particular, the absence of a tax-exempt minimum, the regressive nature of the tax deduction system, and lower personal income tax rates on passive income compared to labor income. Based on the need to overcome these obstacles, proposals for improving the personal income tax have been formulated to ensure tax fairness.