The need for a tax reform of the Personal Income Tax in Mexico is inevitable, evidently the structure of the tax system in Mexico is complex and burdensome compared to other modern tax systems. In order to make the tax structure more equitable and proportional, and to improve the distribution of the tax burden, as well as to adapt the legal framework in tax matters in an efficient manner that serves as a lever for development, it is convenient to simplify the tax provisions by optimizing voluntary compliance with tax obligations. There are several ways to improve the Mexican tax system. This project focuses on the analysis of the principles of equity and proportionality in income tax, and its impact on the taxpaying capacity of salaried individuals.