The primary purpose of creating a preliminary draft audit report is to facilitate communication with management of the area under review. This draft allows for discussion and feedback on the findings, recommendations, and any potential misunderstandings or disagreements before the final report is issued. It helps ensure that the final report is accurate, fair, and reflects the input of both the auditors and management. Reference:
The IIA's International Standards for the Professional Practice of Internal Auditing (Standards), specifically Standard 2410 - Criteria for Communicating.
The IIA's Practice Guide on Communicating Results.