We analyzed the age structure of effective income tax rates using Taxing Wages published by OECD and The Statistical Yearbook of National Tax of Korea. We found that the effective income tax rates of Korea are lower than those of most of OECD countries. However, the effective tax rates for the elderly are higher than those of non-elderly, because under the current income tax system, tax relieves are provided primarily through tax deductions, which benefit high-income earners more than low-income earners. It is also because of the tax arbitrage which allocates tax deductions to high-income earners within a household. Therefore, we suggest a structural revision of personal deduction, employment income deduction, and reinforcement of the role of tax credits, to improve the efficiency and equity by lowering tax burden of the elderly, who earn less than non-elderly and whose labor supply elasticity is high.