兩稅合一制下，為避免公司保留其盈餘不分配，就公司未分配盈餘加徵10% 以之配套， 然而，自申報2010 年營利事業所得稅起，營利事業所得稅稅率由25% 調降至17%，未 分配盈餘仍維持加徵10%，如此一來，營所稅最高邊際稅率與綜所稅最高邊際稅率差距， 由原7.5% 擴大到14.7%。本文主要研究目的，在探討調降營所稅率後，是否造成公司為 規避股東個人綜合所得稅，減少發放股利，而保留公司盈餘。研究結果顯示，不論以總 股利發放率、盈餘配股發放率、或現金股利發放率衡量，公司於調降營所稅率後皆顯著 減少股利發放率。此外，本研究進一步發現，股利發放穩定的公司，其總股利發放率不 因是否調降營所稅率而有所不同，但盈餘配股與現金股利具替代效果。

Taiwan has implemented an integrated income tax system, allowing income taxes paid by corporations to offset personal income taxes paid by shareholders on their dividends. However, an additional 10% surtax on undistributed retained earnings is levied to prevent corporations from retaining earnings. In 2010, a tax reform act reduced the corporate income tax rate from 25% to 17%; however, the additional 10% surtax remained unchanged. This tax amendment broadened the difference between corporate and personal income tax rate from 7.5% to 14.7%, thereby increasing the incentive to retain earnings. The purpose of this study is to investigate whether firms retained their earnings rather than distributing them to reduce the tax burden of investors. The results indicate that the payout ratios of total dividends, stock dividends, and cash dividends decreased significantly after the corporate income tax rate was reduced. In addition, the results suggest that a stable dividend policy exerts moderating effects on total dividend payout ratios. However, substitution effects are observed between stock dividends and cash dividends.