Non-audit services and knowledge spillover: evidence from audit hours and billing rates
研究了从审计公司购买非审计服务是否通过知识溢出提高审计效率，发现非审计服务比例与审计工时和费用降低相关，且不损害审计质量。
Using audit hours from firms listed on the Korea Exchange as a direct proxy for audit effort, this study examines whether non-audit services (NAS) purchased from audit firms improve audit efficiency. Our results reveal that the ratio of NAS fees to total fees paid to audit firms is associated with lower audit hours and audit fees, but it is not significantly related to audit billing rates. The reduction in audit effort associated with NAS is more pronounced when NAS provided are audit-related, and for clients who hire Big 4 auditors, have short-tenured auditors, and report a profit. Further, using path analysis and multiple audit quality proxies, we find no evidence that NAS adversely affect audit quality, either directly or indirectly via their impact on audit effort. Collectively, our evidence supports the view that the joint provision of NAS and audit services enhances audit efficiency without compromising audit quality.