Effective and deterrent methods of combating VAT fraud are crucial for the undisturbed functioning of EU internal market, provision of sound legal framework for taxpayers and protection of the integrity of the fiscal systems of the Member States. Artificial intelligence, algorithms and other technological developments involving big data analysis provide potent tools, which can assist tax administrations in enforcing taxpayers' compliance and preventing fraudulent activities with an unprecedented efficiency and effectiveness. However, reliance on such tools in exercise of State's powers must respect fundamental rights of taxpayers, such as the right to fair trial. This article examines the potential risks and necessary guarantees for the consistency with the provision of the VAT Directive and for the protection of the right to fair trial in the context of new technologies and enforcement of tax laws. The issue is analysed from the perspective of European Union Law and is based on an example of a Polish algorithm-based automated system of detection of VAT fraud.