Abstract
The article examines income taxation as more than a fiscal instrument. In modern legal systems, it also functions as a mechanism through which the state defines justice, solidarity, public responsibility, and the permissible limits of redistribution. The purpose of the research is to determine how historical development, constitutional principles, political structures, and legal traditions have shaped different concepts of tax justice in the Federal Republic of Germany and the Republic of Kazakhstan. The methodological basis of the study includes comparative legal analysis, the historical-legal method, the formal-legal method, systemic analysis, and the interpretation of normative legal acts. The research draws on constitutional provisions, income tax legislation, doctrinal approaches, and institutional mechanisms of tax policy in both countries. The article identifies two models of tax justice: the German socially oriented model, grounded in the principle of ability to pay and the constitutional principle of the social state, and the Kazakhstani fiscal-stabilization model, historically associated with administrative simplicity, budgetary stability, and economic manageability. The central conclusion is that tax justice is shaped by the historical, political, and legal characteristics of the state and directly affects the content, direction, and legitimacy of tax policy.