The purpose of this research is to examine how the regulation of electronic tax system in Indonesia can prevent tax avoidance, and what are the impacts and legal protection of the system. This research uses a normative legal research method with two approaches: statutory and conceptual. The data used are secondary data that consist of primary, secondary, and tertiary legal materials. The data analysis technique used is deductive data analysis. The research results show that the electronic tax system in Indonesia can prevent tax avoidance by making the tax administration more efficient, transparent, accountable, and compliant, and by improving the coordination and cooperation between national and international institutions in exchanging tax information. However, the electronic tax system in Indonesia also has some legal gaps that can be exploited by taxpayers to avoid or reduce their tax obligations, such as transfer pricing, thin capitalization, treaty shopping, and tax haven. Therefore, the government needs to take measures to close the legal gaps, both at national and international levels, by implementing various legal provisions and government instruments that regulate the electronic tax system and prevent tax avoidance. The impacts and legal protection of the system are related to the challenges and obstacles in implementing the electronic tax system, such as infrastructure, human resources, budget, and legal, technical, and social issues. Therefore, legal protection for taxpayers and the government in the electronic tax system is needed to ensure legal certainty, justice, and benefit.