I came up with $485 by using TurboTax (TT) to fill out form 8615. Form 8615 and worksheets haven't been updated, in TT, yet, so the correct amount (for 2019) is $464, rather than $485 (the 2018 amount).
The short cut (to using the form) looks like this:
The first $1100 is not taxed $0
The next $1100 is taxed at 10% (the child's rate), so $110
The next $2600 (first trust bracket) is taxed at 10% $260
The next $390 (5190-4800) is taxed at 24%, so $94
$464
So, the "kiddie tax penalty" is $55 ($464 minus the $409 [10% of $4090] the student "shoulda" paid).
