本研究主要在探討近年來兩大租稅改革：兩稅合一制及最低稅負制之施行對上市公司外資持股比率之影響，是否降低外資持有我國上市公司股票之意願，影響我國企業的股權結構。 兩稅合一制施行後，消除股利所得之重複課稅，國內法人股東與自然人實質稅負減輕；但根據所得稅法第七十三條之二規定，非中華民國境內居住之個人、在中華民國境內無固定營業場所及營業代理人之營利事業，其獲配股利所含之稅額，不得扣抵其應納稅額，外資無法享受股東可扣抵稅額消除重複課稅的好處，外資在台投資實質總稅負仍維持為40%，較境內自然人股東之實質稅率6%~40%為高，股東可扣抵稅額比例愈高，外資損失越大。再者，最低稅負制施行主要影響對象為外資持股最多的電子業，且最低稅負制之施行對於公司補繳之稅負，外資股東也無法享受股利抵稅權。故可推論兩稅合一制、最低稅負制之施行及股東可扣抵稅額與上市公司外資持股比率應呈負向關係。 本研究之樣本為民國85年到民國95年及最低稅負制前、後之台灣上市公司。主要實證結果彙整如下： 1、兩稅合一制之施行及股東可扣抵稅額與上市公司外資持股比率呈負向關係，最低稅負制之施行與上市公司外資持股比率呈正向關係，但其效果應為股價指數之影響所致而非最低稅負制之施行；又最低稅負制施行後，外資仍偏好持有公司有效稅率低於10%之股票。 2、另外以民國93年到民國95年資料額外檢測，最低稅負制下限制投資抵減金額之效用，推論投資抵減金額在最低稅負制施行後與上市公司外資持股比率應呈負向關係，實證結果為負向關係但不顯著。 / The objective of this study is to examine whether the implementation of the Imputation Tax System and Alternative Minimum Tax System will affect the willing of foreign investors to invest in listed companies. The sample of this study consists of firms listed in the Taiwan Stock Exchange from 1996 through 2006. The empirical results in this research are summarized as follows: 1、 The implementation of the Imputation Tax System and a firms' imputation tax credit ratios have a negative impact on the percentage of foreign ownership in listed companies, but the implementation of Alternative Minimum Tax System has a positive impact on that. We conduct further examination and find the increasing effect of the percentage of foreign ownership is more rely on the effect of stock index than that of the implementation of Alternative Minimum Tax System. Further, foreign investors still prefer to invest in listed companies whose effect rates are lower than 10%. 2、With the implementation of Alternative Minimum Tax System, the use of investment tax credit was restricted. The empirical result of this study shows that after the implementation of Alternative Minimum Tax System, the investment tax credit has a negative but not significant impact on the percentage of foreign ownership in listed companies.

我國所得稅法自民國八十七年一月一日開始實施兩稅合一制度。這原本是政府一項消除重複課稅的美意，但是仍受到多方批評。其爭議點就在於「未分配盈餘加徵百分之十營利事業所得稅」這項配套措施的實施。許多專家學者認為，對企業的未分配盈餘課稅，不利於企業內部資金的累積，進而影響其創新活動的投入與產出。而財政部卻持有不同的看法。 基於上述爭議，本研究以迴歸模式探討「未分盈餘加徵百分之十營利事業所得稅」制度的實施，對企業創新活動的影響。經實證結果發現： 1.對企業未分配盈餘加徵10%營利事業所得稅，確實會影響企業資本形成，降低其創新活動。因此，為求稅制良善，促進國家經濟發展，政府對於稅制之設計應謹慎為之。 2.以高科技產業和傳統產業比較，高科技產業由於兩稅合一未分配盈餘加徵10%營利事業所得稅制度的實施，其創新活動較制度實施前縮減，且縮減程度明顯大於傳統產業。此結果顯示，高科技產業顯然可謂新稅制下的最大受害者。因此，對高科技產業之未分配盈餘加以課稅，無疑是形成其創新活動的絆腳石、增加其營運上的風險。政府對此情況，應予正視。 3.以融資受限公司和融資未受限公司比較，兩稅合一之未分配盈餘加徵10%營利事業所得稅制度對融資受限公司之影響不大。經分析樣本特性，發現融資受限公司的獲利能力較差，因此租稅課徵對於其所造成的影響較低。因此可推論，獲利能力差之融資受限公司的創新活動受到非租稅因素的影響比租稅因素來得大。 關鍵字：未分配盈餘加徵百分之十營利事業所得稅，兩稅合一，創新活動 / In response to the public concern, Taiwan has adopted the imputation tax credit system since January 1st, 1998. Although the new tax reform can eliminate double taxation, the implementation of additional 10% surtax on undistributed surplus earnings has engendered lots of comments. Based on the disputations resulted from the new tax system, we conduct an empirical research analyzing the impacts of the implementation of additional 10% surtax on undistributed surplus earnings on the enterprises’ innovation. The empirical results in this research can be summarized as follows: 1. Imposing 10% surtax on corporate undistributed surplus earnings has adverse effect on capital accumulation, in turn leading to reduction in incentive of enterprises to conduct innovative activities. 2. Compared to the traditional industry, adverse effect of this new system is more profound for firms in the high-tech industry. The results indicate that high-tech industry is the major victim under the new tax reform. Therefore, imposing additional 10% surtax on high-tech industry will be an obstacle to enterprises’ growth and increase its operating risks. 3. Compared to unconstrained firms, we find out that the new tax system have less effects on constrained firms. Owing to considering the poor profitability, we can infer that non-tax factors have greater influence on the innovation of constrained firms relative to tax factors. Key words: additional 10% surtax on undistributed surplus earnings, the imputation tax credit system, innovation

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.