Ohio Rev. Code Ann. § 3119.87

The parent who is the residential parent and legal custodian of a child for whom a child support order is issued or the person who otherwise has custody of a child for whom a child support order is issued immediately shall notify, and the obligor under a child support order may notify, the child support enforcement agency administering the child support order of any reason for which the child support order should terminate. Nothing in this section shall preclude a person from notifying the agency that a reason for which a child support order should terminate is imminent. With respect to a court child support order, a willful failure to notify the agency as required by this division is contempt of court.