Bottom line: No change. Income categories are paying almost exactly the same share of federal taxes as before. Millionaires actually pay a tiny bit larger share in the new bill.
Given the distributional hue and cry, frankly, it is a surprise to me just how tiny -- far below measurement errors -- the changes are.
One can argue whether this is the "right" measure of progressivity or redistribution, whether a tax cut should include a change in which income categories pay what share. But it summarizes the facts, which are stubborn things. Shares of federal taxes paid by income groups do not change. Millionaires get bigger dollar tax cuts exactly to the extent that they pay higher taxes. Period.
Note to those outside the beltway: The Joint Committee on Taxation is the committee set up by Congress to evaluate tax policy. Most criticism I've seen of its calculations lately come from the right.