his article provides a theoretical and comparative analysis of the regressivity of the tax burden structure and its impact on the shadow economy. Using data from 152 countries, the study examines the relationship between the tax burden, its structural composition, and the size of the shadow economy across regions and income groups. The findings indicate that, rather than the overall level of the tax burden, its structural composition, particularly a high share of indirect taxes and insufficient progressivity of direct taxation, intensifies the regressivity of the tax system and contributes to the expansion of the shadow economy. The results suggest that optimizing the structure of the tax burden, ensuring an appropriate balance between direct and indirect taxation, and enhancing the social equity of the tax system are important prerequisites for reducing the size of the shadow economy.