The Contribution of Internal Audit as a Determinant of External Audit Fees and Factors Influencing This Contribution

Despite extensive research on the determinants of external audit fees, there is little empirical evidence on the effect of internal audit contribution on the external audit fee. Using a cross-sectional regression model based on prior audit fee research, this study provides evidence that internal audit contribution is a significant determinant of the external audit fee. Further, a second model that provides evidence on the determinants of internal audit contribution is developed and tested. This second model indicates that internal audit contribution is influenced by internal audit quality and, conditional on the level of inherent risk, the availability of internal audit and the extent of coordination between internal and external auditors. These results are based on a unique data-set comprised of publicly available data matched with survey responses from internal and external auditors affiliated with 70 non-financial services Fortune 1000 firms. The sample includes all of the former "Big 6" international accounting firms and clients from twenty-nine different industries.