Undertegnelsen af akterne vedrørende Kongeriget Spaniens og Republikken Portugals tiltrædelse fandt sted den 12. juni 1985 om formiddagen i Lissabon i Jeronimos-klosterets buegang og om eftermiddagen i Madrid i kongepaladset under overværelse af kong Juan Carlos.
The signing of the acts relating to the accession of the Kingdom of Spain and of the Portuguese Republic took place on 12 June 1985, in the morning in Lisbon in the cloister of the Monastery of Jerónimos, and in the evening in Madrid at the Royal Palace in the presence of King Juan Carlos.