Should I move money from my child's UTMA account into a 529 plan?

You can, but there's a catch. Custodial (UTMA/UGMA) assets legally belong to the child, so moving them into a 529 requires opening a custodial 529, which keeps the child as owner and still counts more heavily against financial aid than a parent-owned 529. Also, because UTMA assets can't simply be gifted away from the child, you generally must liquidate the investments first, potentially triggering capital gains taxed under the kiddie tax rules the IRS applies, before contributing cash to the custodial 529. The upside is future growth becomes tax-free for education and the money gets steered toward college rather than becoming the child's to spend at 18 or 21. Weigh the one-time tax cost and aid treatment against the tax-free growth. A tax professional can help you decide if the conversion is worth it for your situation.