其他情況不變下，現金股利發放將使企業喪失投資機會，股利發放為企業使用權益資金成本機會成本。因此，股利發放率與企業權益資金成本為正相關。 我國自1998年1月1日起施行兩稅合一，採設算扣抵制。對於企業未分配盈餘加徵10%營利事業所得稅。本研究探討實施兩稅合一前後，股利發放率與企業權益資金成本為正相關是否因對企業未分配盈餘加徵10%營利事業所得稅而減弱及在產業間減弱程度不同。 本研究實證結果為：1.兩稅合一實施後，股利發放率和企業權益資金成本的正向關係會減弱。企業不論採行募股或舉債方式來籌募資金，在企業保留盈餘不分配而被加徵營利事業所得稅10％公司稅而增加額外稅負，降低了盈餘分配與否之差異性，企業股利發放使用權益資金較稅制改變前機會成本為低。2.高科技產業在兩稅合一後股利發放率和公司權益資金成本正向關係相較傳統產業大幅減弱。在設算扣抵制下盈餘分配時，租稅優惠形成公司階段股東可扣抵餘額較少，僅是遞延稅賦效果，發放現金股利企業使用權益資金機會成本較稅制改變前小，高科技產業在兩稅合一後股利發放率和公司權益資金成本正向關係大幅減弱。 ;Ceteris paribus, the opportunity cost of paying cash dividends refers to the forgone benefits that could result from making an investment with the payout. Thus, cash dividend payout is positively associated with cost of equity. In Taiwan, the integrated income tax system, which adopts dividend imputation and imposes additional 10％ surtax on undistributed retained earnings, became effective from January 1, 1998. This study is to investigate whether the positive association between cash payout and cost of equity is mitigated under the integrated income tax system. Our results show that the positive association between cash payout and cost of equity is mitigated after the integrated income tax system, suggesting that the dividend imputation and additional 10％ surtax lowers the opportunity cost of paying cash dividends. Besides, we find that the mitigating effect is more profound in the high-tech industry. While high-tech companies in Taiwan, which enjoy the tax credit of investment, distribute cash dividend with less imputation credit than counterparts of other industries, high-tech companies have less opportunities cost of paying cash dividends after implementation of integration of income tax system.
