A bit more groundwork here. I know, I know, I'm breaking the cardinal rule not to use Wikipedia as a source-- but I'm only using it for summarizing and quick reference. For example, we ought to note how not-so-popular the legislation was on arrival...
But it has now been nearly a year since the act passed. Did critics' predictions come true?
"On average, in 2027 taxes would change little for lower-and middle-income groups and decrease for higher-income groups. Compared to current law, 5 percent of taxpayers would pay more tax in 2018, 9 percent in 2025, and 53 percent in 2027."
"If it is financed with spending cuts or other tax increases, TCJA will, under the most plausible scenarios, end up making most households worse off than if it had not been enacted."
That is, modest tax cuts for now-- sharp tax increases for later.
"Evidence from past changes in federal taxes, from cross-national comparisons, and from the experiences of individual U.S. states all argue strongly that wages for typical Americans will not benefit from the TCJA."
Just a (large) side note here—that “experiences of individual U.S. states” segment of the quote above is referencing states including Kansas and its recent tax cut "experiment" under Gov. Brownback.