소득분포와 표준화세율이 조세누진성에 미치는 영향

Silber(1994) analyzed progressivity indexes derived from Lorenz or concentration curves as a function of a linear operator called G-matrix. He expressed changes in progressivity indexes between two tax regimes or two time periods as changes in income distribution, standardized tax rates. The standardized tax rate is defined as the tax rate for a group of income recipient divided by the average tax rate for the entire population. The analytical model developed by Silber(1994) is complicated when applied to accounting researches. The graphical technique of Iyer et al.(2008) to analyze changes in progressivity indexes is also not a generalized mathematical approach. This paper suggests new methodology to analyze changes in such progressivity indexes as the Kakwani index and the Suits index and empirically applies them into the tax data of 225 Korean listed companies over the 2001-2007 periods. Among the components of changes in the indexes, a change in income distribution is called the income distribution effect. A change in the standardized tax rate is called the standardized tax rate effect. The empirical results are as follows. First, among changes in progressivity indexes, the income distribution effect is positive whereas the standardized tax rate effect is negative. Second, the correlation analysis for the statistical significance test of the first results reveals that the income distribution effect shows a significant positive correlation with the changes in the both indexes. The standardized tax rate effect has a significant positive correlation only with the changes in the Kakwani index. The results can be summarized. The income distribution effect has led to an increase in the indexes whereas the standardized tax rate effect has marginally led to a decrease in the indexes.