公共轉移與所得稅制是國家藉以縮減貧富差距或擴大中產階級的 主要政策工具，而公共政策未發揮應有效果的國家，可能較仰賴私人 移轉的重分配效果。文獻上尚未有同時比較上述政策對臺灣、韓國與 日本中產階級影響的研究，本研究使用2005-2013 年的盧森堡家戶所 得資料庫，比較2000 年中期公共移轉、私人移轉及所得稅對三個國 家中產階級的影響，此外也分析臺灣與韓國的跨時變化。主要研究發 現包括：一、所得階層別的家庭組成分析顯示，臺灣與韓國下層階級 的老人單人家戶與老人夫妻兩人家戶佔率明顯高於中層與上層階級； 日本由於公共年金制度相對成熟，所以這個現象較不明顯。二、日本 的公共移轉擴大中產階級與減少下層階級的力量大於臺灣與韓國，相 對的臺灣與韓國的私人移轉擴大中產階級與減少下層階級的力量大於 日本。此外，臺灣與韓國2012-2013 年公共移轉的所得重分配效果有 減弱的現象。三、臺灣與韓國的所得稅制失功能，所得稅與社會保險 費擴大中產階級的作用不及公共移轉。臺灣2013 年的所得稅與社會 保險費竟反而使中產階級減少，且使下層階級增加。

Public transfers and income tax systems are primary policies and tools of the country to reduce economic inequality and to expand the middle class. However, in some countries where public policies fail to exercise effect, private transfers for income redistribution become more effective. Previous study less compared the effect of the public policies on the middle class among Taiwan, South Korea, and Japan. Hence, this paper used the Luxembourg household income database from 2005 to 2013 to analyze the effects of public transfers, private transfers, and income tax on the middle class among Taiwan, South Korea, and Japan in the 2000s. Additionally, this paper compared the time variant difference between Taiwan and Korea as well. The research results were: 1. Analysis of the family composition of the different social classes (categorized according to their income) showed that in Taiwan and South Korea, the proportion of older adults living alone (one person) or older couples living together (two people) in the lower class was significantly higher than those in the middle and upper classes. In Japan, because of the presence of the public annuity system, this phenomenon was less pronounced. 2. In Japan, the effect of public transfers on increasing the middle class and decreasing the lower class was greater than that in Taiwan and South Korea. By contrast, the effect of private transfers on expanding the middle class and diminishing the lower class was greater in Taiwan and South Korea than in Japan. In addition, the income redistribution effect of public transfers in Taiwan and South Korea decreased in 2012-2013. 3. In Taiwan and South Korea, the income tax systems were relatively ineffective: the effects of income tax and social insurance charges expanding to the middle class were less than those of public transfers. In 2013, income tax and social insurance charges actually decreased and increased the populations of the middle and lower classes in Taiwan, respectively.