Since 2014, local income tax has been converted into independent tax from the type of surtax on the national income tax such as individual and corporate income tax. The introduction of independent local income tax in the name of taxation sovereignty of local government has increased tax administrative costs such as collection costs and taxpayer cooperation costs. Current local income tax shares taxation object and tax base with national income tax. Local government can just exercise tax autonomy through adjustments of flexible tax rate and tax credit and reduction. However, if the local governments plunge into tax competition by exercising taxation sovereignty, the taxation system of local income tax will become more complicated and taxpayer burden will grow heavier. This study indicates defects and directions for improvement in relation to the conversion of local income tax into independent tax. The main points of this study are as follows. First, compared with the previous surtax on national income tax, the current independent local income tax is more complicated and increases tax administrative costs such as collection costs and taxpayer cooperation costs. Surtax or tax sharing system may be suggested as alternatives to the current independent local income tax. Second, the more local governments expand tax autonomy, the more harmful effects of tax competition among local governments and tax administrative costs are expected. Therefore, tax autonomy of local government should be restricted appropriately. Third, the requirement of accompanying documents which is almost same as for the national tax report aggravates taxpayer s burden in reporting tax base and tax amount of local income tax. So, the local government should get such documents in cooperation with National Tax Service instead of laying a burden on the taxpayers. Fourth, considering that local income tax shares tax base with national income tax, tax investigation for local income tax by the local government may result in wasted administrative power and double the burden on the taxpayers. Thus, investigation for taxable income should be conducted by National Tax Service and tax appeal proceedings should be improved to prevent repetitious work between central and local government. Lastly, the discriminatory application of tax incentives between individual and corporation undermines tax equity.