Legal Question in Credit and Debt Law in California

It sounds like this court date was some time ago, and he has not been making any payments since he went to court, or at least very few. Even if someone makes the court ordered payments, interest accrues as long as the arrears are owed. The courts charge interest and try to make it as uncomfortable as possible to stay in arrears, since children still need to eat and have a roof over their head. It really isn't fair to put the entire burden of worrying about caring for a child on one parent. Your son can either call child support services and go over the account with them himself, or hire an attorney to find out what is going on and determine whether there are any accounting errors that need correcting.