The succession rights of extramarital descendants recognised after the execution of a will: effective protection or merely formal equality?

Abstract

The constitutional recognition of equal status for all children has become one of the cornerstones of Spanish succession law following the 1978 Constitution and the reform introduced by Act 11/1981. Nevertheless, the establishment of filiation after the execution of a will—or even after the opening of the succession—raises significant challenges in ensuring that such equality results in genuinely effective patrimonial protection. Drawing on the Spanish Supreme Court Judgment No. 2495/2026 of 27 May 2026, this article examines the legal protection afforded to descendants born out of wedlock whose filiation is recognised at a later stage, particularly in relation to preterition and lifetime gifts previously made to other descendants. The paper analyses the retroactive effects of filiation, the tension between biological truth and legal certainty, and the limitations of traditional succession law mechanisms—such as collation, reduction of excessive lifetime gifts and the protection of the compulsory share—in restoring patrimonial equality among forced heirs. It argues that succession equality should be assessed from a threefold perspective: legal, patrimonial and procedural. While normative equality has been fully achieved, the article concludes that significant obstacles remain to securing substantive equality where filiation is established only after succession planning has already taken place.