ECJ Ruling: Invalidity of tax reporting obligations for lawyers regarding cross-border planning

1. The facts

   The case stems from an appeal filed before the Belgian Constitutional Court by several bar associations, as reported by the specialized press. At the heart of the dispute was the national implementation of the DAC6 Directive, which required intermediaries to report aggressive tax planning schemes. Under the contested rules, a lawyer invoking professional secrecy to avoid direct reporting to tax authorities was still obliged to inform other intermediaries involved, such as banks or accountants, of their reporting duties. The procedural stage culminated in a preliminary ruling on validity, leading the Court of Justice to rule, in case C-694/20, on the legitimacy of this information burden in light of fundamental rights guaranteed by the European Union.

2. 

   The rules at play

   The central provisions of the case are three:

   1. The European directive on tax cooperation (DAC6), whose provision on mandatory notification required intermediaries exempt due to professional secrecy to notify their exemption to other intermediaries, so they could proceed with tax reporting;
   2. The EU Charter of Fundamental Rights, in which the protection of respect for private life and communications forms the legal basis for legal professional secrecy;
   3. National implementing legislation, meaning the domestic rules that reflected the EU framework now declared partially invalid. Violation of these rules originally entailed heavy administrative fines for the non-compliant professional.

3. What the jurisprudence says

   European case law has clarified that professional secrecy is not just an ethical duty but a pillar of the rule of law. Established guidelines emphasize that the confidentiality of communications between lawyer and client enjoys reinforced protection, which cannot be restricted by administrative transparency needs except in exceptional and strictly necessary cases. The Court ruled that forcing a lawyer to reveal the existence of advice on a specific tax operation to third-party intermediaries constitutes an unjustified interference in the fiduciary relationship. This orientation confirms that the protection of secrecy extends to out-of-court advice and not just to defense in a pending trial.

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8. What it teaches professionals

   The ruling suggests some fundamental operational lessons:

   1. Mandate review: it is advisable to update engagement letters clearly specifying that the lawyer will not notify third-party intermediaries by virtue of professional secrecy;
   2. Client information: professionals must clarify to the client that the burden of tax reporting or notification to other consultants falls exclusively on the assisted party;
   3. Monitoring of EU case law: the prevalence of the Charter of Fundamental Rights can be successfully invoked against internal rules or directives that compress legal prerogatives.

References: DAC6Carta dei diritti fondamentali dell'UENormativa nazionale di recepimentoCausa C-694/20

Editorial oversight: Avv. Federico Papa·ICAMUpdated 20 September 2026Content drafted with AI support and subject to editorial source checks. Despite these controls, inaccuracies may remain: reports and rectification requests are welcome. Report a correction