This paper estimates earned income tax burden of different income groups, top 0.01%, 0.1%, 1%, 5%, 10%, and bottom 90% during 1963-2011. Under current income tax system, income tax burden has a rising trend even with the reduction of tax rate and the expansion of exemptions. Under the progressive tax system, the increase in nominal income results in bracket creep which shifts taxpayers to the brackets with higher tax rates. It is called “hidden tax hike” since income tax burden increases without explicit tax rate increase. This paper decomposes the change in income tax burden into two parts due to tax system revision and bracket creep and finds that the rising income tax burden is mainly due to the “hidden tax hike”. This tax increase based on the bracket creep is against a tax principle that emphasizes the consensus of society for the tax increase. It also weakened progressiveness of income tax by hitting middle and low income groups more heavily than high income group because most of wealthier taxpayers’ income is already taxed at the top marginal tax rate.