The Internal Audit Function provides an independent assessment of operations, activities, and internal controls within Prince William County Government. The Internal Audit Function assists the County in accomplishing its objectives by bringing a systematic and disciplined approach to evaluating and improving the effectiveness of the organization's risk management, internal control, and governance processes. Reporting directly to the BOCS, the Internal Audit Function provides independent, value-added, risk-based audits designed to review, test and evaluate the County's operations.

The audits involve a systematic review of County departments and activities, and the development of objectives to evaluate performance and identify opportunities for improvements in their effectiveness and efficiency. The Internal Audit Function governs itself by adherence to applicable Professional Standards, such as the Institute of Internal Auditors. This mandatory guidance constitutes principles of the fundamental requirements for the professional practice of internal auditing and for evaluating the effectiveness of the Internal Audit Function’s performance.