Abstract This study aims to evaluate legal certainty in the application of Value Added Tax (VAT) on e-commerce transactions in Indonesia. Using a normative legal approach and qualitative descriptive methods, this study examines the effectiveness of the implementation of applicable tax provisions, especially based on the Regulation of the Minister of Finance Number 81 of 2020 concerning Tax Provisions in the Core Tax Administration System. The research findings indicate that although the relevant regulations are available, their implementation still encounters various obstacles. The main challenges include the lack of understanding of business actors, especially MSMEs, regarding their tax obligations, as well as the existence of regulatory loopholes related to cross-border transactions and entrepreneurs who are not yet registered as Taxable Entrepreneurs (PKP). Therefore, this study proposes the need to strengthen regulations, increase education and socialization to business actors, and optimize supervision to improve tax compliance, so that the e-commerce sector can contribute more significantly to the national economy. Keywords: legal certainty, added valuetax (VAT), e-commerce.