El principio de irretroactividad en derecho tributario

Resum

The study of retroactivity and its boundaries constitutes a classic and fundamental issue in Tax Law. Nowadays, this topic is subject to an intensive debate regarding how it proves the prolific constitutional and European case law related to the matter. This study carries out a systematic analysis of the non-retroactive principle in Tax Law, in the fields of application and production of tax norms - as a general supplementary rule and as a constitutional principle - whilst at the same time distinguishing between the substantive, procedural and penal character. The investigation (which has an interdisciplinary and internationally comparative law nature) deals with the retroactivity notion, grandfathering and with the constitutional boundaries of the tax retroactivity effect. Concurrently, the study is complemented with the analysis of the retroactivity of administrative acts and court decisions, with special reference to the temporal effects of the declaration of an anti-constitutional character of tax laws