According to IIA guidance, the internal audit charter is a formal document that defines the internal audit activity's purpose, authority, and responsibility. It establishes the internal audit activity's position within the organization, including the nature of the chief audit executive's functional reporting relationship with the board; authorizes access to records, personnel, and physical properties relevant to the performance of engagements; and defines the scope of internal audit activities. Final approval of the internal audit charter is done by the board, not just senior management. Furthermore, the charter might describe the expectations for communicating the results of the quality assurance and improvement program, which ensures that the internal audit activity continues to operate effectively and efficiently.References: IIA Standard 1000: Purpose, Authority, and Responsibility; and Standard 1300: Quality Assurance and Improvement Program.