The chief audit executive (CAE) is responsible for the approval of the engagement objectives and scope in internal auditing. While senior management, the head of customer service, and the board of directors may provide input and have interests in the audit engagement, it is ultimately the CAE who has the final authority to approve the objectives and scope. This ensures that the internal audit activity remains independent and that the engagement aligns with the overall audit plan and organizational priorities.

The Institute of Internal Auditors (IIA) Standard 2010 - Planning

IIA Standard 2200 - Engagement Planning