The primary guideline for preparing audit engagement workpapers is that they should be understandable to another internal auditor who was not involved in the engagement. This ensures that workpapers are clear, complete, and sufficiently detailed so that another auditor can understand the work performed, the evidence gathered, and the conclusions reached without needing additional explanations.

IIA References:

IIA Standard 2330: Documenting Information requires internal auditors to document relevant information to support the conclusions and engagement results. The Practice Advisory 2330-1 emphasizes that workpapers should be understandable and provide a clear trail of the audit process and conclusions, facilitating peer review and quality assurance processes.

The IIA’s Practice Guide on Audit Documentation suggests that workpapers should be prepared with the understanding that another internal auditor, unfamiliar with the work, may need to review them for quality assurance or other purposes.