審計市場集中度與審計品質之探討

Audit Market Concentration and Audit Quality

自從美國安隆(Enron)案導致審計產業供給者數量減少之後，歐、美主管機關均憂慮其不利影響，同時冀望學術界提供更多證據。近年來已有相關研究進行探討，然而並未獲得一致的結果，本研究納入台灣審計市場之特色，以事務所層級及簽證會計師層級衡量集中度，探討審計市場集中度與審計品質之關聯。本文以1987 年至2020 年之上市（櫃）公司為觀察值進行測試，實證結果發現無論是事務所或簽證會計師層級集中度，均會減緩客戶裁決性應計數之認列，代表在集中的審計市場審計品質較高。進一步切割樣本年度，實證結果顯示當服務內容或業務量較少時，集中度與審計品質有正向關聯，但當事務所服務內容增加、或簽證會計師服務內容與業務量增加時，集中度則與審計品質有負向關聯。本文執行多項額外測試與敏感性分析後，其結果均與主要結果相同。本文之實證數據與實務意涵提供學術界、財務報表使用者，以及主管機關參考。

Since the demise of Arthur Andersen, regulators in Western countries have been concerned with the negative effect of having fewer auditors in the market. Studies investigating the relationship between audit market concentration and audit quality have reported mixed findings. This study explores the characteristics of the audit market in Taiwan and examines the association between audit market concentration and audit quality at the audit firm and audit partner levels. By analyzing companies listed from 1987 to 2020, we reveal the negative associations between concentration at both levels and clients’ discretionary accruals. By dividing the observations into four periods, the empirical results indicate that the concentration level is positively correlated with audit quality when the business content or business volume is less. But the concentration level becomes negatively associated with audit quality when audit firm's business content increases, or when audit partner’s business content and business volume increase. The results of additional tests and sensitivity analyses are the same as the main tests. This study provides empirical evidence and implications for academic researchers, financial statement users, and regulators.