Section: Volume C

The best possible engagement objectives are those derived from a comprehensive risk assessment that incorporates inputs from both senior management and the company's risk function experts. This approach ensures that the internal audit objectives are aligned with the organization's strategic priorities and risk landscape. By combining insights from senior management with the technical expertise of risk function experts, the internal audit activity can develop well-rounded and relevant engagement objectives that address the most significant risks facing the organization.
:
The Institute of Internal Auditors (IIA) Standard 2010 - Planning: "The chief audit executive must establish risk-based plans to determine the priorities of the internal audit activity, consistent with the organization's goals." IIA Practice Guide on "Internal Audit Planning"

Confirmation letters are generally considered the most reliable source of documentary evidence because they involve direct verification of information with an independent third party. This type of evidence is less prone to bias or manipulation compared to internal documents like policy statements or remittance advices.
IIA Reference:
IIA Standard 2310: Identifying Information requires that internal auditors gather sufficient, reliable, relevant, and useful information to support engagement results. Third-party confirmations, such as confirmation letters, are considered highly reliable because they come from independent sources.
The Practice Guide on Audit Evidence highlights that external confirmations provide strong evidence of the accuracy of the information being audited.

Preparing a detailed audit program is a critical component of engagement planning. This program outlines the specific procedures and tests that the internal auditor will perform to evaluate the effectiveness of controls. It ensures that the audit is conducted systematically and thoroughly, addressing all relevant risks and objectives.
A detailed audit program provides a clear roadmap for the audit, helping to ensure that all necessary areas are covered and that the audit's objectives are achieved.References:
* The Institute of Internal Auditors (IIA) - Standards for the Professional Practice of Internal Auditing, Standard 2201 - Planning Considerations