The Court of Audit holds the permanent Secretariat of the European Organisation of Supreme Audit Institutions (EUROSAI) since its establishment in 1990. EUROSAI is the Regional Group of the INTOSAI that groups together the Supreme Audit Institutions (SAIs) of 50 Members, including the European Court of Audit. 

As a full member of the International Organization of Supreme Audit Institutions (INTOSAI), the Court of Audit is actively involved in several of its committees and subcommittees devoted specifically to the implementation of the goals of the Strategic Plan of the Organization 2017-2022 and has worked in several of its "taskforces".

The Court maintains relations with the External Audit Bodies of the European Union, including the European Court of Audit, through the Contact Committee of the Supreme Audit Institutions of the European Union.  It also acts as a liaison between the Court of Audit and the bodies of the Spanish Administration.

The Court of Audit has bilateral relationships with other Supreme Audit Institutions and performs various actions with international organizations.  It is especially notable for its participation in collaborative projects with Supreme Audit Institutions and for conducting the external audit of international organizations.