The Types of Law Involved in the Principle of Tax Legality

This paper examines the constitutional status of the principle of tax legality through a doctrinal and comparative analysis of case law in the European Union and constitutional doctrine and judicial practice in Germany and Taiwan. The principle serves as a constitutional safeguard ensuring that tax obligations have a statutory basis. By examining the Danish, Związek, Fiat, Atlas, and Engie cases, these rulings clarify the scope, limits, or constitutional dimension of this principle within EU law. The paper also examines the constitutional frameworks in Germany and Taiwan, including the application of this principle on administrative circulars. The paper concludes that consistently applying the principle of tax legality across these jurisdictions strengthens the constitutional guarantee of legal certainty and the foreseeability of tax obligations.