How can I be sure my child support is being spent on my children?

You can’t. There is no obligation to account for the use of child support and, in fact, there is no obligation to use child support for the children. However, once support is paid, the custodial parent is responsible for the expenses of the children and if these expenses are not being met, an application can be made to court for the failure of the custodial parent to properly support the children.