The decision by the Court of Justice of the European Union (ECJ) in San Domenico Vetraria has outlined the contrast between the VAT Directive and the Italian law as far as the VAT treatment of secondment of personnel is concerned. The way the decision will be implemented, however, remains unclear. In this article, the authors intend to provide a brief overview of the entire matter by retracing the law and the case law developments until the recent judgments of the Italian Supreme Court (Supreme Court), which have transposed the interpretation given by the ECJ.