Internal Audit Outsourcing: A Literature Synthesis and Future Directions

The internal audit function (IAF), which has traditionally been an in‐house function, is increasingly being outsourced to outside consultants, in line with global trends for other services. This study synthesises research on the outsourcing and co‐sourcing of internal audit services over the last three decades, and suggests directions for future research. It draws from professional and academic literature to highlight the nature of organisations that outsource the IAF, and the main reasons behind the outsourcing decision. The study further examines the financial impact of outsourcing, as well as its impact on financial reporting, internal audit quality and auditors’ independence. The study shows widespread adoption of outsourcing of internal auditing services, largely due to the perceived cost benefits as well as perceived improved access to specialised internal auditing resources. There are mixed findings on the impact of outsourcing of internal auditing services on quality, cost, independence and availability of resources. This study contributes to internal and external audit, corporate governance and outsourcing literature in general, by synthesising the existing research and providing a roadmap with which to understand the origins, development, present state and impact of outsourcing of internal auditing.