It depends. If the children's interest income was less than $2,200, you do not need to report it and they do not need to report it.
In general, to report your children's unearned income on your return, follow these steps: How do I report my child's investment income?
Use this IRS Interactive Tax Assistant Guide to verify that he can be claimed as your dependent.
The rules following the Tax Cuts and Jobs Act are more favorable than the pre-TCJA rules for Form 8615. For more information, click on the article: SECURE Act Retroactive Change to Kiddie Tax
[Edited 3/31/2020 | 7:08 AM PST]