The impact of labour unions on external auditor selection and audit scope: evidence from the Korean market

We examine whether labour unions influence external auditor selection and audit scope. As a major user group of financial information, labour unions likely demand financial information of high quality and thus high-quality audits. As a union’s request for wage increases is likely strong when a firm is performing well, management facing wage negotiations with the labour union has incentives to manipulate earnings downward and may therefore prefer auditors who allow more discretion. Using union data unique to Korea during 2005–2008, we find that firms with a stronger labour union tend to choose higher-quality auditors (i.e. Big N or industry specialist auditors). We also find that unionization is negatively (positively) associated with positive (negative) abnormal audit fees and audit hours, and the effects are more pronounced when the union is stronger and more active. Given that departures from normal audit fees and audit hours in either direction arguably impair audit quality, this finding is consistent with our prediction of unions’ demand for high-quality audits. Overall, our findings suggest that labour unions play an important role in determining audit quality.