由於會計準則與稅法規定的不一致，產生了財務與稅務差異，因而在資訊揭露上，而有所得稅費用、遞延所得稅資產、遞延所得稅負債及當期應納所得稅等科目；另由於二稅合一的實施，股東可享有的股東可扣抵稅額，又獨立於公司帳戶之外，使得所得稅相關資訊部份包含在財務報表內，部份獨立於財務報表外。 　　對於投資人而言，所得稅的相關科目與公司價值具有價值攸關性，而本研究欲探討代表「現在帳內」的應付所得稅、「未來帳內」的遞延所得稅資產、負債、及代表「過去帳外」的股東可扣抵稅額，何者與公司價值較具攸關性。 　　本研究以民國八十八年至九十二年上市櫃公司為樣本，以JA Test進行實證分析，結果如下： 1. 納入應付所得稅之模型，在全部樣本、大規模公司及電子業下，較納入遞延所得稅資產、負債之模型，與公司價值較攸關。 2. 納入應付所得稅之模型，在大規模公司及電子業下，較納入股東可抵稅額之模型，與公司價值較攸關。 3. 納入遞延所得稅資產、負債之模型，在全部樣本、大規模公司、電子業與非電子業，較納入股東可抵稅額之模型，與公司價值較攸關。

依據財務會計理論，附註揭露為整體財務報表的一部份，其目的在提供投資人進行企業評價時所需之攸關資訊。兩稅合一制度實施後，不僅使稅賦型態轉變，會計原則中也新增附註揭露股東可扣抵稅額之規定，因此提供了驗證資本市場與財務報表揭露的機會，本研究即針對股東可扣抵稅揭露是否具有價值攸關性進行測試。 本研究以87年為樣本年度，分析資料完整的317家上市公司，透過Ohlson模型來檢測股東可扣抵稅額之價值攸關性，並處理Ohlson模型中兩個重要的information dynamics，以異常盈餘（xa ）及其他資訊（v）做為模型中的自變數，將財務分析師之財務預測（analysts’forecasts）做為Ohlson模型中其他資訊（other information）之代理變數，以捕捉Ohlson模型中其他資訊對股價的影響。最後，考慮產業及公司規模兩項因素，觀察紡織業與電子業對股東可扣抵稅額揭露之反應以及公司規模對於價值攸關性研究的影響。 實驗結果顯示，無論以現金基礎或應計基礎衡量股東可扣抵稅額，其揭露均具價值攸關性，投資人的確使用財務報表附註揭露中有關股東可扣抵稅額之資訊於企業評價上。其次，異常盈餘與其他資訊皆能捕捉股價之變動。最後，在紡織業與電子業中雖未觀察到股東可扣抵稅額之揭露具有攸關性，但公司規模的因素則無論在全體樣本或各別產業中皆具影響力。 / According to modern accouning theory, footnote disclosures are an intergrated part of the overall financial statements. The purpose of footnote disclosures is to provide value-relevant information in assisting investors’ valuation process. After Taiwan’s 1998 Tax Reform, which intergrates the individual and corporate taxes, the current GAAP requires a footnote disclosure of imputation credits (IC). This provides a good chance to test how Taiwan’s stock market reacts to such disclosuer. The main purpose of this study is to examine the value relevance of IC disclosure to investors’ equity valuation. This study uses Ohlson’s (1995) model to analyze 317 firms listed on Taiwan’s Stock Exchang (TSE) during 1998. To estimate the abcdrmal earings and other information (captured by analysts’ forcasts), this study adopts Dechow, Hutton, and Sloan’s(1999) methodology. We also investigate the effects of industry and firm size on the value relevance of IC disclosure. The empirical results reveal three findings. First, there is a positive association between IC and stock price in TSE. Therefore, the IC disclosure is value relevant to investors’ equity valuation. Second, abcdmal earnings and other information can both explain stock price behavior. Finally, when we focus our sample on the textile and high-tech industries, no significant association between IC disclosure and stock price can be found. When we further consider firm size, however, the value relevance of IC disclosure becomes significant. In other word, the value relevance of IC disclosure may be affected by firm size.

本論文探討兩稅合一制所增設的兩個機制，即稅額扣抵比率及加徵保留盈餘稅對上市公司股利發放、資本結構以及公司租稅規劃的影響。首先以數學模式推導出兩稅合一制下這兩個機制與股利發放率及負債權益比率之間的關係，再據以建立研究假說，而後進行兩步驟多變量程序之實證測試。研究所獲致的結果包括： 　　一、兩稅合一制實施後，上市公司稅額扣抵比率與總（盈餘）股利發放率呈正相關，且上市公司稅額扣抵比率愈高者，其總（盈餘）股利發放率、現金股利發放率及盈餘配股發放率皆較兩稅合一制實施前高。由於公積配股並不受兩稅合一制實施的影響，故本文也發現兩稅合一制實施前後公積配股率並無顯著差異。整體而言，兩稅合一制實施後，總（盈餘）股利發放率、盈餘配股發放率及公積配股率較實施前減少，而現金股利發放率較實施前增加。進一步的分析顯示現金股利發放率的增加係受到健全股利政策的推行影響，而盈餘配股發放率的減少可能是受到股票股利緩課取消的影響。 　　二、兩稅合一制實施後，符合促進產業升級條例第八條及第九條規定之投資方案，選擇股東投資抵減之公司並無顯著多於選擇五年免稅之公司，可能原因為選擇五年免稅有利於公司現金流量及每股盈餘的金額。此一結果雖與預期方向相反，但也顯示政府原先擔心公司會選擇股東投資抵減而造成鉅額稅收流失的疑慮並未獲得實證支持。但從兩稅合一實施後公司股權結構的變動分析顯示，公司法人持股比率較實施前增加，而僑外投資持股率較實施前減少，支持公司在不同股東身分稅負差距的考量下，會有股權結構移轉之租稅規劃，以降低股東所負擔的稅負。 　　三、兩稅合一制實施後，上市公司稅額扣抵比率愈高者，股東所享扣抵權愈多，則舉債租稅利益愈少，因而總負債權益比率將降低；而上市公司保留盈餘比率愈高者，所課徵的保留盈餘稅愈高，舉債利息的租稅利益反而增加，會造成總負債權益比率增加。本文的實證結果也顯示，兩稅合一制實施後，上市公司稅額扣抵比率愈高者，其總負債權益比率較實施前低；而上市公司保留盈餘比率愈高者，其總負債權益比率較實施前高。 　　綜合本論文實證結果顯示，兩稅合一制實施後，稅額扣抵比率的機制確實其有消除股利所得重複課稅的效益，進而提高公司股利發放的意願，並且有助於公司資本結構的改善。但是，政府對於未分配盈餘加徵 10％營利事業所得稅的規定卻不利於公司資本的累積，反而提高舉債的租稅誘因，也可能抵銷稅額扣抵比率降低舉債的效果，值得政府深入檢討對公司未分配盈餘課稅的不利影響。 / Enacted in 1998, the Integrated Income Tax System has two important features, i.e., the imputation tax credit to shareholders and the 10% surtax levied on undistributed earnings. Using two-step multivariate regression, this study exmines the impacts of these two features on corporations' dividend payout, tax planning, and capital structure. The findings of this study are as follows : 　　1. After implementation of the Integrated Income Tax System, the imputation tax credit ratio is positively related with total dividends payout ratios. Companies with higher imputation tax credit ratios tend to pay out more cash dividends and earnings stock dividends, ceteris paribus. However, there appears no significant relation between the imputation tax credit ratio and capital stock dividends. On average, after implementation of the Integrated Income Tax System, stock dividend payout ratios, including earning stock dividends and capital stock dividends, are decreased, but cash dividend payout ratios are increased. The increase in cash dividend payout may be affected by the balance dividend policy by the SEC, which require corporations to pay out greater proportions in cash dividends. The decrease in earning stock dividends may be due to the cancellation of the deferral of tax on stock dividends. 　　2. After implementation of the Integrated Income Tax System, inconsistent with the expectation, companies still prefer the five-year tax exemption to the investment tax credits. The results suggest that companies' choices are affected more by such factors as corporate cashflows and earnings per shares. However, after implementation of the Integrated Income Tax System, there is a significant change in stockholder structures, with the ratios of corporation stockholders being increased while the ratios of oversea stockholders being decreased. The opportunity of tax arbitrage will have a significant impact on corporations' stockholder structures. 　　3. After implementation of the Integrated Income Tax System, for companies with higher imputation tax credit ratios, their stockholders will have greater tax benefits, and, hence, the tax benefit for companies to use debt financing is decreased. Conversely, companies with higher ratios of retained earnings will bear more tax burdens on the 10% surtax levied on undistributed earnings; therefore, the tax benefit of debt financing is increased. The empirical results support that, ceteris paribus, companies with higher imputation tax credit ratios tend to have lower debt-to-equity ratios, while companies with higher ratios of retained earnings tend to have greater debt-to-equity ratios. 　　In summary, after implementation of the Integrated Income Tax System, the imputation tax credits reduce the double taxation on stockholders' dividend income and, hence, improve corporations' capital structure. However, the 10% surtax on undistributed earnings may result in opposite effect on corporations' capital structure. The findings of this study have important implications for the government to take into account the potential adverse impacts resulted from taxes levied on corporations' retained earnings.