An Analysis of Horizontal and Vertical Equity of the Alternative Minimum Tax

我國自95年1月1日起施行「所得基本稅額條例」。最低稅負制之實施目的，係為使適用租稅減免規定而繳納較低所得稅負或甚至免稅之公司或個人，至少負擔一定比例之所得稅，可兼顧既有產業或社會政策，並適度減緩過度適用租稅減免規定造成的不公平。本文以最低稅負制實施前後各一年為比較標的，分析比較最低稅負制實施前後之租稅公平性，包含租稅水平公平程度和租稅垂直公平程度。 本文以台灣經濟新報資料庫(TEJ)之93年、96年兩年度的上市、櫃公司財務報告相關資料為研究樣本，並選用租稅負擔變異係數比值(Coefficient of Variation Ratio)作為租稅水平公平之衡量工具；Gini係數作為租稅垂直公平衡量工具。本文研究結果顯示，最低稅負制實施後之各區間租稅水平公平程度，大多優於最低稅負制實施前之情形；而以整體稅制而言，最低稅負制實施後亦較實施前更具有租稅水平公平。在租稅垂直公平程度方面，本文之結果亦顯示，最低稅負制實施後之整體租稅垂直公平程度，優於最低稅負制實施前之情形。本文之研究結果可作為我國政府過去租稅政策成效之回顧以及未來相關租稅政策制定時之參考。Taiwan has adopted the Income Basic Tax Act since January 1st 2006. The purpose of the new income tax system is to make the companies or individuals, who only pay little or even negative income taxes because of tax relief, have at least a certain percentage of the income tax burden. Therefore, the Income Basic Tax Act could appropriately mitigate the unfairness caused by tax relief. The main objective of the thesis is to examine the horizontal equity and the vertical equity of the Income Basic Tax Act. The thesis chooses one year before the Income Basic Tax Act and one year after that as the research sample periods to compare and analyze. Using“CV ratio” (Coefficient of Variation Ratio) as the horizontal equity measure and the Gini coefficient as the vertical equity measure, the thesis analyzes the data of the listed companies and the OTC companies from the 2004 and from the 2007 finacial reports collected by Taiwan Economics Journal (TEJ) to measure the horizontal equity and the vertical equity of income tax systems before and after the Income Basic Tax Act. The findings indicate that the tax system after the Income Basic Tax Act is more horizontally equitable than that before the Income Basic Tax Act in most income levels and for the whole tax system. The findings also indicate the tax system after the Income Basic Tax Act yields more vertical equity than that before the Income Basic Tax Act