我國實施兩稅合一的主要目的為消除重覆課稅、增進租稅公平、提高投資意願和降低稅制對企業財源籌措方式之影響。在兩稅合一制度下，以往在獨立稅制前題下，所發展出稅與公司融資政策間的理論關係，不見得適用於我國，因在兩稅合一下，如Officer(1994)認為將減少負債稅盾的相對利益。另外，Bellamy (1994)表示實行兩稅合一之後，將改變公司的動機，從獨立稅制下追求最大化的稅後利潤到兩稅合一之後的追求最大化稅前利潤。因此，亦即表示由獨立課稅制變更為兩稅合一制下的本國公司，其融資政策將隨之調整、改變。
本研究除了針對全體上市櫃樣本進行實證分析，以了解是否兩稅合一的實施是否將降低稅制對企業財源籌措方式之影響，並減少公司的負債水準。由於高科技具有高保留盈餘率與低有效稅率下，其權益資金成本可能受到公司稅與個人所得稅合併之利益較小，而受到未分配盈餘10%之營所稅的負面影響較大，因此，相較於一般產業而言，負債水準下降的較少。此外，因兩稅合一並不適用外國股東，所以本研究將檢驗是否兩稅合一的影響是否會因股權結構(外國股東持股比率)而有所不同。
最後，由於以往研究，多以直接檢測兩稅合一前後的負債水準來驗證兩稅合一對公司負債水準的影響，但此方法會將其它經濟性等因素納入衡量，所以可能會有所偏誤。因此，本研究使用Thomas et al (1996)的研究方法來衡量兩稅合一對負債水準的影響。
實證結果方面，在兩稅合一的實施是否將降低稅制對企業財源籌措方式之影響上，大多得到支持且因產業的不同有所差異，但不受股東結構的影響。另一方面，在兩稅合一是否減少公司負債水準上，其將受產業效果的影響，但不因股東結構的不冋而有所差異。

參考文獻
一、中文文獻
中華民國九十年證券暨期貨統計要覽，財政部證券暨期貨管理委員會著，民國90年。
中華民國華僑及外國人投資對外投資、對外技術合作、對大陸間接投資大陸產業技術引進統計月報，經濟部投資審議委員會著，民國93年。
兩稅合一方案介紹，財政部著，民國87年(網址:http://www.ntat.gov.tw /Chinese/07download/02.htm)。
林世銘，兩稅合一前後產業租稅環境與經營績效之比較，財稅研究，第三十四卷 第三期 民國91年，頁64-78。
商景明、林義欽、藏仕維，兩稅合一與資本結構理論，財稅研究，第三十二卷 第三期，民國89年，頁1-27。
國民經濟動向統計季報，行政院主計處著，民國93年。
許崇源、俞洪昭、洪盈斌和戚務君，兩稅合一制度對公司屬性與股票報酬關聯性之影響，會計評論，民國89年，頁81-101。
陳明進，我國租稅優惠對營利事業租稅負擔之影響。管理評論、第二十二卷、第一期、民國92年，頁127-151。
陳明進、汪瑞芝和蔡靜文，我國兩稅合一前後公司有效稅率之研究，財稅研究，第三十五卷，第五期，民國92年，頁120-134。
黃允治，外資在我國從事證券投資之相關規範及未來展望，證券暨期貨月刊，第二十一卷，第十二期，民國92年，頁4-15。
黃瑞靜、徐守德、廖四郎，兩稅合一對公司價值、股利政策和資本結構之影響---動態資本結構模型之應用和台灣產業的實證研究。管理評論 第二十卷，第二期，民國90年，頁57-81。
蔡文麗，兩稅合一對跨國企業之影響，財稅研究，第三十二卷，第四期，民國89年，頁91-102。
二、英文文獻
Bellamy, D.E. (1994) Evidence of imputation clienteles in the Australian equity market , Asia Pacific Journal of Management,11, 275-287.
Boadway, R. and, N. Bruce (1992) Problems with integrating corporate and personal income taxes in an open economy, Journal of Public Economics, 48 , 1, 39-66.
Bradley, M.G.., G.A. Jarrell and H.K. Kim (1984) On the existence of an optimal capital structure: theory and evidence, Journal of Finance,39, 3, 857-880.
Cordes, J. J. and S. M. Sheffrin (1983) Estimating the tax advantage of corporate debt, Journal of Finance, 45, 1, 95-105.
Chen , M. C., S. Lin, and T.H. Chang(2001) The impact of tax-exempt stock and land capital gains on corporate effective tax rates. Taiwan Accounting
Review, 2, 33-56.
Crutchley,C.and R. Hansen(1989) A test of the agency theory of managerial ownership, corporate leverage, and corporate dividends, Financial Management, Vol.18, No4, 36-46.
Damon, R.M. and L.W. Senbet (1988) The effect of taxes and depreciation on corporate investment and financial leverage, Journal of Finance, 45 ,2 , 357-370.
DeAngelo, H. and R.W. Masulis. (1980) Optimal capital structure under corporate and personal taxation, Journal of Financial Economics, 8 , 3-25.
Dhalwat, D., R Trezevant,. and Wang, Shiing-wu. (1992) Taxes investment -related tax shields and capital structure, Journal of the American Taxation Association, 14 , 1 , 1-21.
Fisher, E.M., R.L. Heinkel, and J. Zechner (1989) Dynamic capital structure choice theory and tests, Journal of Finance, 31, 1,37-52.
Givoly, D., C. Hayn, A.R. Ofer and O. Sang (1992) Taxes and capital structure evidence from firms response to the tax reform act of 1986, Review of Financial Studies, 5 , 2 , 331-355.
Gordon, R.H.(2001) Do the tax affect corporate debt policy? evidence form U.S corporate return data, Journal of Public Economics, 82 ,195-224.
Gourevitch, H.G. (1977) Corporate tax integration the European experience, Tax Lawyer, 31, 1, 65-112.
Graham, J. R. (1999) Do personal taxes affect corporate financing decisions？Journal of Public Economics, 73,147-185.
Gravelle, J. G. (1992) Corporate tax integration issues and options, Washington D.C Congressional Research Service.
Long, M.S. and L. B. Malitz (1985) Investment patterns and financial leverage in corporate capital structures in the United States, edited by Benjamin M. Friedman,325-351.
Kim, W. S.and E.H. Sorensen(1986) Evidence on the impact of the agency costs of debt in corporate debt policy, Journal of Financial and Quantitative Analysis,Vol.21, No.2, 131-144.
MacKie-Mason, J.K. (1990) Do taxes affect corporate financing decisions? Journal of Finance,.45,.5,1471-1493.
Mandilaras, A. and P. Levine (2001) Public Debt and Inflation :The Role of inflation -sensitive instruments, The Manchester School Supplement, 1-21,1463-6786. 195 -224.
Marsden, A. , D. Pacey and J. Wong (1994) The impact of dividend imputation on earnings management of New Zealand listed companies, New Zealand Journal of Taxation Law and Policy,1,69-86.
Marsh, P.(1982) The Choice between equity and debt an empirical Study , Journal of Finance 37 No 1, 121-144.
Martin, F. and D. Frisch (1977) Corporate tax integration the estimated effects of capital accumulation and tax distribution of two integration proposals, National Tax Journal, 31, 1,37-52.
Mayers, S.C. (1997) The determinants of corporate borrowing, Journal of Financial Economics, 5, 2, 147-175.
Modigliani, F. and M.H. Miller (1963) Taxes and the cost of capital: a correction. American Economic Review ,433-443.
Monkhouse, H.L. and P. Warburg (1993) The cost of equity under the Australian dividend imputation tax system, Accounting and Finance,1-18.
Myers,S.C. and N.S. Majluf (1984) Corporate financing and investment decisions when firms have information that investors do not have, Journal of Financial Economics,13, 2 , 187-221.
Officer, R. R. (1994) The cost of capital of a company under an imputation tax system, Accounting and Finance, 34 , 1-17.
Pozdena, R.J.(1987) Tax policy and corporate capital structure, Federal Reserve Bank of San Francisco Economic Review, 4,37-51.
Prevost, A. , R.P. Rao and J.D. Wagster (2002) Dividend imputation and shareholder wealth：The case of New Zealand, Journal of Business Finance &Accounting, 29 ,1079-1103
Shum, P. (1996) Taxes and corporate debt policy in Canada : an empirical
Investigation, Journal of Finance, 37 , No 1, 121-144.
Thomas, D. W. , C. T Schulman. , K. F Sellers. and D. B Kennedy (1996) Effects of tax I ntegration and capital gains tax on corporate leverage, National Tax Journal, Vol. 49 Issue 1, 31-54.
Titman, S. and R. Wessels (1988) The determinants of capital structure choice, Journal of Finance, Vol. 45 , No.1 , 1-19.
Twtte. G. (2001) Capital structure choices and taxes：Evidence from the Australian dividend imputation tax system, International Review of Finance, 2(4), 217-234.
Wansley, J.W.,M.C. Collins and A.S.Dutta(1996)，Further Evidence on The Relation Between Corporate，Ownership structure and debt policy，managerial finance,Vol.22, No.2 ,56-74.
Wilkinson, B. R. , S. F. Cahan and G.. Jones (2001) Strategies and dividend imputation：The effect of foreign and domestic ownership on average effective tax rates, Journal of International Accounting, Auditing & Taxation , 10,157-175.