Characteristics of the internal audit and external audit hours: evidence from S. Korea

Purpose Using 5,055 sample firm-years in Korea between 2009 and 2013, this paper aims to examine the association between the characteristics of the internal audit and the number of external audit hours as a proxy for audit efficiency. Design/methodology/approach This study is motivated by the International Standard on Auditing No. 610: “Using the work of internal auditors”. This auditing standard guides external auditors in using the work of internal auditors to obtain audit evidence and consult internal auditors for direct assistance. The authors expect that external audit efficiency will increase when the work of competent internal auditors is used. Findings The authors find that the number of internal auditors relative to the number of employees is associated with the number of external audit hours. This result suggests that the greater the availability of internal auditors, the greater their contribution will be to the financial statement audit and the more efficient the audit. The authors find evidence that external auditors use the work of internal auditors with accounting and legal expertise to improve audit efficiency. They also find some evidence that the work of internal auditors with greater availability is more effective during initial external audit engagements. Originality/value This study adds to the extant literature on the contributions of internal auditors to external audits by using archival data and by measuring audit effort using a large database of audit hours. In addition, our findings have practical implications for firms and external auditors who are evaluating the role and value of using the work of internal auditors. The authors also believe that the findings will be of interest to regulators or auditing standards boards.