Internal auditors generally determine the priority of the areas within the engagement scope by assessing the risk of those areas. This involves estimating the likelihood of a risk occurring and the potential impact of that risk on the organization. High-risk areas with a high likelihood of occurrence and significant impact are prioritized to ensure that critical risks are addressed promptly. This risk-based approach to prioritization helps ensure that the audit resources are focused on the most significant areas, enhancing the effectiveness and efficiency of the audit.
Reference:
The Institute of Internal Auditors (IIA) - Standards for the Professional Practice of Internal Auditing, Standard 2010 - Planning