營利事業所得稅率調降和盈餘管理之研究

Abstract

立法院於民國98年5月1日三讀通過修正所得稅法，將營利事業所得稅稅率自25%調降為20%，自99年度起適用。若管理階層希望降低稅務負擔，使公司價值最大化，此稅率調降之幅度可能給予管理階層十足的誘因去遞延盈餘。本研究欲探討管理階層是否因此而將98年度的部分盈餘遞延至較低稅率的年度。另外，以債務契約假說、政治力量假說等來設立變數，辨認與盈餘管理相關聯之因素。 本研究樣本之估計期間從85年至95年，測試期間為96年至98年。本研究採用Modified Jones Model 估計非裁量性流動應計數（ discretionary current accruals），自總流動應計數中扣除，得到裁量性流動應計數，本研究將其視為盈餘管理之代理變數，利用統計方法，驗證其與變數之關聯性，得到以下結論： 1. 管理階層可能在稅率調降前一年度（98年）向下管理盈餘，將該期盈餘遞延到較低稅率之年度。 2. 在稅率調降前一年度的裁量性流動應計數與債務比率呈正向關係。 3. 在稅率調降前一年度的裁量性流動應計數與公司規模呈正向關係。 4. 在稅率調降前一年度的裁量性流動應計數與管理階層持股比率呈負向關係。

The Legislative Yuan of Republic of China changed Income Tax Act to reduce income tax rate from 25% to 20%, which became effective in 2010. Income tax rate reduction would have provided management with substantial incentives to defer income from 2009 to 2010, as a way to minimize tax costs. This study investigates whether earnings of 2009 were managed downwards in response to tax rate reduction, and to examine which type of firms are more likely to conduct earnings management. The estimation period of the sample is from 1996 to 2006, and test period 2007 to 2009. Discretionary current accruals, which are estimated by Modified Jones Model, are used as a proxy for earnings management. Based on empirical results, this study has four conclusions: 1. Managers tend to deliberately decrease 2009 earnings in order to minimize tax costs. 2. Discretionary current accruals in the year proceeding to tax rate reduction are positively related to debt levels. 3. Discretionary current accruals in the year proceeding to tax rate reduction are positively related to firm size. 4. Discretionary current accruals in the year proceeding to tax rate reduction are negatively related to levels of manager ownership.