自2018年起，我國廢除已實行19年的「兩稅合一設算扣抵制度」，回歸「古典課稅制」。是因為「兩稅合一制」並未達到其最初的稅改意旨:提高企業投資意願，也為了順應目前各國所得稅制的改革潮流，接軌國際。
本研究以2015年到2020年台灣上市櫃公司為研究對象，以現金有效稅率(Cash ETRs)作為避稅代理變數，探討此租稅改革是否對企業的避稅動機產生影響；並以控制權與盈餘分配權的偏離程度作為公司治理的代理變數，探討稅制改革之後，企業是否會因公司治理程度的不同，而產生不同程度的避稅行為。
本研究實證結果發現，2018年稅制改革以後，企業的避稅程度顯著增加；公司治理程度較高的企業，稅改之後，企業的避稅程度顯著降低，而公司治理程度較差的企業，稅改之後，企業的避稅程度顯著增加，其中，公司治理程度較差的企業之避稅增加幅度大於公司治理程度較佳的企業的避稅降低幅度；另外，稅制改革之後，家族企業的避稅程度也較一般企業低。

Since 2018, our country has abolished the 19-year-old " Integrated Income Tax System" and returned to the "Classical Taxation System". This is because the " Integrated Income Tax System" has not achieved its original purpose of tax reform: to increase the willingness of enterprises to invest, and to conform to the current reform trend of the income tax system in various countries and interface of the worldwide.
This study takes Taiwan listed companies from 2015 to 2020 as the research object, and uses the Cash Effective Tax Rates (Cash ETRs) as a proxy variable for tax avoidance to explore whether this tax reform has an impact on the tax avoidance motives of enterprises; The degree of deviation is used as a proxy variable of corporate governance. After the tax reform, whether enterprises will have different degrees of tax avoidance due to the different degrees of corporate governance.
The empirical results of this study found that after the tax reform in 2018, the degree of tax avoidance of enterprises increased significantly. The degree of tax avoidance of enterprises with a high degree of corporate governance decreased significantly after the tax reform, while the degree of tax avoidance of enterprises with a poor degree of corporate governance decreased after the tax reform. The degree of tax avoidance of enterprises has increased significantly. Among them, the increase of tax avoidance of enterprises with poor corporate governance is greater than the decrease of tax avoidance of enterprises with better corporate governance. In addition, after the tax reform, the tax avoidance degree of family enterprises is also lower than that of ordinary enterprises.

一.中文文獻
林嬌能和許彩蓮，2011，家族企業與租稅規劃之關聯性，會計學報 4, 23-49.
黃美祝和陳緯霖，2017，代理觀點下避稅行為與公司價值之關聯性－來自中國的實證研究，當代會計 18, 155-185.
二.英文文獻
Amiram, D., A. M. Bauer, and M. M. Frank, 2019, Tax Avoidance at Public Corporations Driven by Shareholder Taxes: Evidence from Changes in Dividend Tax Policy, Accounting Review 94, 27-55.
Chen, S. P., X. Chen, Q. Cheng, and T. Shevlin, 2010, Are family firms more tax aggressive than non-family firms?, Journal of Financial Economics 95, 41-61.
Claessens, S., S. Djankov, and L. H. P. Lang, 2000, The separation of ownership and control in East Asian Corporations, Journal of Financial Economics 58, 81-112.
Desai, M. A., and D. Dharmapala, 2006, Corporate tax avoidance and high-powered incentives, Journal of Financial Economics 79, 145-179.
Dyreng, S. D., M. Hanlon, and E. L. Maydew, 2008, Long-run corporate tax avoidance, Accounting Review 83, 61-82.
Fama, E. F., and M. C. Jensen, 1983, Separation of ownership and control, The journal of law and Economics 26, 301-325.
Fan, J. P. H., and T. J. Wong, 2002, Corporate ownership structure and the informativeness of accounting earnings in East Asia, Journal of Accounting & Economics 33, 401-425.
Frank, M. M., L. J. Lynch, and S. O. Rego, 2009, Tax Reporting Aggressiveness and Its Relation to Aggressive Financial Reporting, Accounting Review 84, 467-496.
Gompers, P., J. Ishii, and A. Metrick, 2003, Corporate governance and equity prices, Quarterly Journal of Economics 118, 107-155.
Gómez-Mejía, L. R., K. T. Haynes, M. Núñez-Nickel, K. J. Jacobson, and J. Moyano-Fuentes, 2007, Socioemotional wealth and business risks in family-controlled firms: Evidence from Spanish olive oil mills, Administrative science quarterly 52, 106-137.
Jensen, M. C., and W. H. Meckling, 1976, Theory of the firm: Managerial behavior, agency costs and ownership structure, Journal of Financial Economics 3, 305-360.
Jensen, M. C., and R. S. Ruback, 1983, The market for corporate control: The scientific evidence, Journal of Financial Economics 11, 5-50.
Klapper, L. F., and I. Love, 2004, Corporate governance, investor protection, and performance in emerging markets, Journal of Corporate Finance 10, 703-728.
Khurana, I. K. and W. J. Moser, 2009 ,Institutional Ownership and Tax Aggressiveness, Proceedings of American Accounting Association 2010.
La Porta, R., F. Lopez-de-Silanes, and A. Shleifer, 1999, Corporate ownership around the world, Journal of Finance 54, 471-517.
Manzon Jr, G. B., and G. A. Plesko, 2001, The relation between financial and tax reporting measures of income, Tax L. Rev. 55, 175.
Minnick, K., and T. Noga, 2010, Do corporate governance characteristics influence tax management?, Journal of Corporate Finance 16, 703-718.
Rego, S. O., and R. Wilson, 2012, Equity Risk Incentives and Corporate Tax Aggressiveness, Journal of Accounting Research 50, 775-810.
Yeh, Y. H., 2005, Do controlling shareholders enhance corporate value?, Corporate Governance-an International Review 13, 313-325.
Yeh, Y. H., and T. Woidtke, 2005, Commitment or entrenchment?: Controlling shareholders and board composition, Journal of Banking & Finance 29, 1857-1885.