In December 2000, the Permanent Council established the Office of Internal Oversight (OIO) to enhance oversight across the OSCE. The underlying principles governing the work of OIO are incorporated into the OSCE's Financial Regulations, along with a Mandate that sets out the nature, objectives and responsibilities of OIO’s work.

Reporting directly to the Secretary General and wholly independent of all other arms of the OSCE, OIO conducts audits, evaluations and investigations. Working with OSCE executive structures, Secretariat departments and thematic units, OIO seeks to promote efficiency and effectiveness within the framework of the OSCE’s objectives.