Here’s a pretty good explanation of the kiddie tax: https://ttlc.intuit.com/questions/1901223-what-is-the-kiddie-tax-and-do-i-have-to-pay-it
The bad news is that you’re stuck paying the kiddie tax on unearned income for a kid who’s a full-time student (until the year he turns 24) unless his earned income pays more than 50% of his support.