The TaxProf Blog is on top of the real tax cut story [as usual]. Here is the link to the PDF of the congressional report “FEDERAL INCOME TAX SYSTEM IS HIGHLY PROGRESSIVE
AFTER RECENT TAX CUTS“. Of which, the concluding paragraph says:
These IRS data illustrate the steeply progressive nature of the federal income tax. Further, data on the number of non-filers, tax shares and the number of taxpayers effectively paying zero federal income taxes must be considered before any valid distributional evaluation of various income tax proposals or legislation can be made.