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.

The Institute of Internal Auditors (IIA) - Standards for the Professional Practice of Internal Auditing, Standard 2010 - Planning