This study examines the scope of application and the autonomy of tax law as one of the fundamental legal instruments regulating the relationship between the state and taxpayers, as well as ensuring tax justice and economic stability. The research problem focuses on defining the precise framework of the scope of tax law in terms of territory, time, and persons, and analyzing its independence from other branches of law in light of contemporary challenges, particularly globalization and the digital economy. The study aims to analyze the dimensions of the scope of tax law within the Libyan legal system, highlight the characteristics and criteria of the autonomy of tax law, and examine the role of administrative judiciary in ensuring the proper and fair application of tax rules. The research adopts a descriptive-analytical approach to examine and interpret legal texts, in addition to a comparative method to assess selected legal systems and identify best practices. The study concludes that tax law possesses a distinctive autonomous nature that differentiates it from other legal branches. Its scope of application is based on principles such as territoriality and tax justice. Moreover, the effectiveness of tax law depends on legislative flexibility and its ability to adapt to economic and social changes. The study also emphasizes the importance of developing tax legislation and strengthening international cooperation to address tax evasion and double taxation. Keywords: Tax Law, Scope of Application, Autonomy of Tax Law, Tax Justice, Territoriality, Tax Evasion