I think if parents are paying taxes on qualified dividends at 15% (ordinary income between $78,751-$488,850, a pretty broad range), then the TCJA rules are more favorable for a wide range of children's qualified dividend income.
This is my understanding:
Both TCJA rules and pre-TCJA rules have an $1100 standard deduction, with the next $1100 taxed at the child's rate. The rules start to differ above $2200 of unearned income.
TCJA (estate rules):
$0-$2650 (above the first $2200): 0%
$2651-$12950: 15%
$12951+: 20%+NIIT
pre-TCJA:
all of this is taxed at 15% (+NIIT if the parents are at or kicked above the threshold for that)
I'm not an accountant so if anyone has any corrections for the above I'd be happy to hear it. But it seems the TCJA rules will be the same as pre-TCJA rules for those under $2200, and the TCJA rules will be favorable for most people with children's unearned income between $2200 to something north of 2200+12950.
If I understand properly, re-TCJA rules are advantageous for children whose parents have ordinary income under $78,750, or for those with unearned income more like the $32000 example given earlier (I haven't done the math to figure out where the 20% estate rate costs more than the savings at 0-2650).
