근로소득세제 변천과 조세 정책의 경제적 효과 분석

Government reduced tax rates up to 2% point gradually from year 2009 to 2010 and increased highest tax rate from 35% to 38% in 2012 and revised dramatically the income tax system, whose revisions are reduction of earned income deduction rate up to 10% point and change of deduction method into tax credit method on itemized special deductions. The earned income deduction is corresponding to necessary expenses. This paper analyses the economic effects of revisions of income tax system using 2007-2014 earned income tax data of statistical yearbook of national tax, focusing on 2009-2014 results. The economic effects are overall tax burden, tax progressivity and income redistribution. The tax progressivity index is the Kakwani index and the income redistribution index is the Reynolds-Smolensky index. The results are as follows. During 2010-2011, there are no special results. During 2012-2014, average tax rates increased, the Kakwani indexes increased, and the Reynolds-Smolensky indexes increased, which means increased overall tax burden, strengthened tax progressivity, and strengthened income redistribution. So the tax system revisions of 38% highest tax rate, overall deduction of earned income deduction rate and the change of deduction method into tax credit method on itemized special deductions during 2012-2014 can be evaluated as achieving both effectiveness and equity through tax revenue increase, progressive taxation and income redistribution improvement.