In this article, the author analyses the key case law delivered by the Court of Justice of the European Union in the field of EU VAT and seeks to provide the reader and/or the taxable person with a better understanding of the evolution of the good faith doctrine over the past years, from cases such as Kittel to Vikingo. The author evaluates the reasons why the good faith doctrine should be harmonized in the VAT Directive as a general principle of EU VAT law. She, thereafter, proposes that the good faith doctrine should be codified as hard law in article 272 of the VAT Directive relating to the obligations of taxable persons and non-taxable persons.