Congress has passed at least one tax bill each year since 2001 and an average of one tax bill each year since 1940.
Those bills lowered the top individual income tax rate from 91 percent in 1962 to 70 percent in 1980 and to 39.6 percent today.
The top corporate income tax rate was 46 percent in 1980. Today, it is 35 percent.
The Economic Recovery Tax Act of 1981 (ERTA) indexed some parameters of the individual income tax for inflation (effective in 1985), reducing "bracket creep" where inflation pushed taxpayers into ever-higher tax brackets.
The Tax Reform Act of 1986 reduced the number of tax brackets from 11 to two. Tax acts in 1990, 1993, 2001, and 2012 added five more brackets.
Tax acts since 1986 have created the child tax credit; increased the earned income tax credit (EITC) and the dependent care credit; and added tax incentives for retirement savings, education, and health insurance.