What significance does the notification have in the tax area?

Clarify your doubts by consulting your particular case

Administrative acts are presumed valid and, as a rule, produce effects from the date on which they are issued. Their effectiveness is delayed where the content of the act requires it or where effectiveness is subject to notification, publication or higher approval (Article 39(1)–(2), Law 39/2015).

In tax matters, the general administrative notification rules apply together with the special rules in Articles 109–112 of the General Tax Law (Law 58/2003). Notification is essential when the applicable rule makes an act’s effectiveness subject to it. It also informs the taxpayer of the full decision and the available remedies and deadlines.

It is too broad to say that every unnotified act has no legal effect: the effect depends on the applicable rule and the nature of the act. In addition, a notice that contains the full text but omits other required information may take effect when the taxpayer acts in a way that shows knowledge of the decision’s content and scope, or files an appropriate appeal (Article 40(3), Law 39/2015).

Official sources: Law 39/2015, Articles 39 and 40, https://www.boe.es/buscar/act.php?id=BOE-A-2015-10565 ; General Tax Law 58/2003, Articles 109–112, https://www.boe.es/buscar/act.php?id=BOE-A-2003-23186