The European Union was devised to promote competition in the international market environment and ensure balanced allocation of fiscal and political requirements of the Member States. Globalization has led to enabling tax environments through granting of tax benefits by EU Member jurisdictions intended to promote competition in attracting foreign investment, trade, and development. Multinational Corporations may often exploit these tax benefits through various tax arrangement provisions causing a loss of tax revenue. The European Commission is implored to oversee the tax ruling granted by the Member States that is distortionary to the internal market. The Notion of State aid rule Article 107(1) TFEU is adopted as part of the mechanism to combat distortions that leads to tax evasion and harmful tax competition.  This research is intended to analyse the Commission and the General Court’s approach to demonstrate illegal or unlawful State aid through varied and adaptive methodology to tackle emerging complex tax arrangements provisions of Multinational Corporations, notably the Amazon and Engie recent cases. This paper also discusses the identification of potential conflict of laws between the relevant general system of legal rule of the domestic tax legislation and EU Law. Specifically with regards to the determination of whether a tax benefit confers a tax advantage and subsequently if that advantage is deemed selective in nature in a transfer of financial asset undertaking under a certain domestic law. The dynamics of potential abuse of law and aid recovery with the general tax principle of Legality will also be explored.