Corporate Mergers: Article 2504-quater of the Civil Code and Supreme Court Ruling 16689/2025 on the Unassailability of the Deed

Corporate mergers are crucial operations for business growth, but their validity cannot remain uncertain. Article 2504-quater of the Civil Code establishes the "preclusion" to challenge merger deeds once they are registered in the Companies' Register. The Supreme Court of Cassation, with ruling no. 16689 of June 22, 2025, provided an authoritative interpretation, reinforcing the principle of legal certainty in this delicate area.

Absolute Preclusion under Article 2504-quater of the Civil Code

The legislator of the 2003 reform prioritized the stability of extraordinary transactions. Article 2504-quater of the Civil Code ensures that, after registration in the Companies' Register, the merger deed cannot be challenged for most defects. This protects third parties and the certainty of legal transactions, preventing the annulment of already consolidated economic operations. The Court of Cassation, with ruling no. 16689 of 22/06/2025, reiterated the absolute nature of this preclusion, which "heals" almost all irregularities, both those related to the final deed and procedural ones.

The Supreme Court's Ruling: The Sole Exception of Legal Non-Existence

The Supreme Court, in the ruling under review, provided a clear definition of the limits of this unassailability:

In matters of company mergers, Article 2504-quater of the Civil Code imposes an absolute preclusion that concerns both cases where defects inherent directly to the merger deed are alleged, and hypotheses where such defects concern the procedure for forming the deed and its registration, in line with the legislator's preference in the 2003 reform for the mandatory protection, rather than the real protection, of subjective legal situations affected by corporate deeds. Consequently, the scope of the curative effect provided by said provision extends to all forms of non-compliance with the discipline – including procedural aspects – that lead to the approval of the merger resolution and its registration in the Companies' Register, unless any defects or omissions cause such a distortion of the procedure as to make it manifestly unrecognizable in its essential features, even to third parties, thus allowing for the hypothesis of the legal non-existence of the merger deed registered in the register.

The broad "curative effect" of registration covers almost all non-compliances. However, the Court of Cassation establishes an insurmountable limit: the legal non-existence of the deed. This occurs when the procedure is so "distorted" as to make it "manifestly unrecognizable in its essential features." Only in these very rare cases can registration not cure a deed that, in fact, never came into existence.

• Examples of such "distortions" include the complete absence of a merger resolution or registration based on clearly forged documents.

For all other defects, remedies are compensatory, not the invalidation of the deed.

Conclusions

Supreme Court ruling no. 16689/2025 strengthens the stability of registered corporate mergers, a pillar for the market. Article 2504-quater of the Civil Code protects extraordinary transactions, but with a crucial exception: legal non-existence. This underscores the importance of scrupulous procedural compliance. For companies and professionals, the preparatory phase requires maximum attention and legal expertise. Relying on expert consultants is essential to ensure full regularity and prevent any risks.