本研究分成兩部分，研究對象為中國大陸之上市公司，第一部分以2004至2009年之財務資料，探討2008年中國大陸企業所得稅法之實施對中國大陸上市公司平均有效稅率之影響；第二部分以1998至2009年之財務資料，探討中國大陸上市公司是否為了因應企業所得稅法實施對有效稅率的影響，而從事租稅誘因盈餘管理之行為。 第一部分之實證結果發現，中國大陸上市公司之平均有效稅率在2008年企業所得稅法實施後有顯著的下降，表示中國大陸上市公司之有效稅率隨著名目稅率降低而下降。外資持股比例超過20%之上市公司（定義為外資企業），其2008年後之有效稅率上升，且內外資企業之其平均有效稅率之差異有縮小之趨勢。屬於高科技產業之上市公司在2008年企業所得稅法實施後，其有效稅率並未下降；但與除了農林牧漁業外之其他產業相比，高科技產業之上市公司其有效稅率較低。第二部分之實證結果發現，在2008年有效稅率下降之上市公司，其於2008年後的裁決性應計項目較大，有將盈餘遞延認列之傾向。 / This study consists of two research issues. The first part uses the financial statement and capital structure data of China listed companies from 2004 to 2009, to investigate the effects of the implementation of the Law of the People’s Republic of China on Enterprise Income Tax in 2008(hereafter 2008 Income Tax Law). And the second part which uses the financial and capital structure data of China listed companies from 1998 to 2009 investigates if China listed companies take the action of earnings management in response to the implementation of the 2008 Income Tax Law. The empirical findings of the first part show that the average ETRs of China listed companies declined after the implementation of the 2008 Income Tax Law. The listed companies whose proportion of foreign ownership is above 20% (defined as foreign enterprises) increased ETRs after 2008 and the differences in ETRs between domestic enterprises and foreign enterprises are reduced gradually. Further, the average ETRs of China listed companies of information technology industry do not appear to be decreased after the implementation of the 2008 Income Tax Law. However, besides the agriculture, forestry, herding, fishery industries, listed companies of information technology industries remain to have lower average ETRs after implementation of the 2008 Income Tax Law. The empirical findings of the second part show that China listed companies whose average ETRs decreased in 2008 appeared to have greater discretionary accruals after 2008, suggesting those companies shifting earnings to 2008.

本研究以台灣上市櫃公司及分析師投資報告為研究對象，探討會計師忙碌程度與審計品質之關聯性，以及產生學習或互斥效果。審計品質以裁決性應計項目、財務報表重編及迎合或擊敗分析師預期三種特性進行分析。 研究結果發現，會計師忙碌程度與裁決性應計項目、財務報表重編及迎合或擊敗分析師預期皆呈現顯著負相關。此結果表示，會計師忙碌程度愈高，受查公司管理當局進行盈餘管理之可能性愈低。本研究藉此結果推論，會計師忙碌程度愈高，透過累積查核經驗，促進知識改善，產生正向的學習效果，進而提高審計品質。 / This thesis examines the association between the busyness of auditors at partner level and audit quality and whether the association stems from learning effect or crowding-out effect, by using the listed firms’ data and the analysts’ reports in Taiwan. I use the following three measures of audit quality to examine my hypotheses: discretionary accruals, financial restatement, and meet or beat analyst forecast. The empirical results indicate that firms experience lower discretionary accruals, are less likely to restate financial statements and have lower likelihood of meeting or beating analysts’ expectations when auditors are busier. The results are consistent with the notion that auditor busyness is positively related to audit quality. Taken together, the findings provide strong evidence in favor for learning effect rather than crowding-out effect of auditor busyness. Further analyses reveal that the results remain unchanged, regardless of lead auditor busyness or concurring auditor busyness.