In Dubio Pro Tributario/In Dubio Mitius as a Rule of Reasoning in Tax Law Interpretation

The article is devoted to the principle of in dubio pro tributario (the principle of resolving doubts in favour of the taxpayer) as a rule of legal reasoning. The article points out its following two aspects: (1) the evidential aspect whereby it is concerned with resolving uncertainties regarding the proof of facts that are relevant to the determination of the amount of tax and (2) the interpretative aspect whereby it is used to resolve doubts related to the ambiguity of a legal regulation. The article focuses on the second aspect. The authors present how various legal systems have developed different ways of understanding this principle. They point out that it is not a universally applied principle in tax law and that it has been rejected in the case law of the Court of Justice of the European Union (CJEU).