The concept of “foreseeable relevance” is a key element of the standard of transparency in tax matters. It has experienced significant changes in its scope and conceptual interpretation during the last years to ensure a wide exchange of tax informationand ensure the correct application of international agreements and domestic tax law. The interpretation of the extent and limits of the “foreseeable relevance” notion has been at the centre of a series of rulings by the CJEU, which have contributed to defining also the scope of application of Article 47 of the Charter of Fundamental Rights in tax cases and question the judicial control in the so-called “horizontal composite procedures”.

In October 2020, in the joined cases C-245/19 and C-246/19 État luxembourgeois v B and Others,the CJEU introduced new nuances on the type of documentation that has to be exchanged among tax authorities.On 25 November 2021, in case C-437/19 État du Grand-duché de Luxembourg v L, the Courtfocused on the foreseeable relevance of data belonging to groups of taxpayers. The Court issued new criteria to requests of information of a group of taxpayers to avoid being classified under the term of “fishing expeditions”. Both rulings directly affect the taxpayers’ rights and impact on the system of administrative cooperation in tax matters. Furthermore, new criteria have been introduced for group requests in the recently passed Council Directive (EU) 2021/514 of 22 March 2021 amending Directive 2011/16/EU on administrative cooperation in the field of taxation, known as DAC 7. The OECD standards of transparency together with the model convention and its commentaries have been key elements in the shaping of the European scope of information sharing, nurturing its conceptual interpretation and creation of limits.

Both CJEU rulings have also influenced the interpretation and scope of application of the right to an effective remedy contained in Article 47 of the Charter, especially with respect to administrative decisions that oblige taxpayers and other third parties to provide an amount of information that might beregarded as arbitrary or disproportionate. Starting from the Berlioz I ruling (C-682/15), furthermore, one can observe a trend of progressive clarification of question of judicial control of preparatory decisions issued in the context of horizontal cooperation mechanisms (i.e. those in which the process of implementation of EU law takes place exclusively through the interaction between national authorities without the involved of the EU administration).

These cases go to the core of the need to strike a correct balance between, on the one hand, an effective system of administrative cooperation as a vital tool to tackle tax evasion and avoidance, and, on the other hand, the necessity to protect taxpayers’ rights from possible arbitrary and disproportionate procedures and establish a set of clear limits as to which information can and should be exchanged.

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