Ohio Rev. Code Ann. § 3119.39

If a person who has received a notice of medical support enforcement activity under section 3119.35 of the Revised Code fails to make a timely request under section 3119.38 of the Revised Code for an administrative hearing, the notice of medical support enforcement activity becomes a final determination of the child support enforcement agency that issued that notice that no mistake of fact exists in the national medical support notice referred to in the notice of medical support enforcement activity. When an agency's determination becomes final, the agency shall take further action as required by section 3119.41 of the Revised Code.