An internal auditor failed to identify transactions between the parent organization and a subsidiary.

The most likely reason for an internal auditor failing to identify transactions between the parent organization and a subsidiary is a lack of understanding of the organization. Understanding the organizational structure, including relationships between parent and subsidiary entities, is crucial for identifying and evaluating intercompany transactions. A thorough knowledge of the organization ' s operations, financial arrangements, and business processes enables auditors to recognize and properly assess such transactions during their audit engagements.

The Institute of Internal Auditors (IIA) Standards, specifically Standard 1210 – Proficiency.

IIA ' s International Professional Practices Framework (IPPF).

" Internal Auditing: Assurance & Advisory Services " by IIA, Chapter on Understanding the Business and Audit Planning.