If there was an California order or judgment for child support, and a portion of that court ordered support remains unpaid, California law has largely eliminated any "statute of limitations" on collection of that overdue child support, and it may still be due and collectible. Additionally, unpaid child support orders continue to accrue interest at the legal rate for judgments, presently 10% per year, so if there was only $100 remaining due when the child turned 18, 11 years ago, , it's more than $200 now.
If you're the person who owes this money, you should take a copy of the support order, and a detailed history of your payments, to an attorney familiar with this issue.
If there is a court order for the support, the answer is most likely "yes." You should contact the Department of Child Support Services for help with this for free (unless you are the party who owes the money. If you;re that person, the Deparatment of Child Support Services will go after you to pay the money).
