Ohio Rev. Code § 3929.85
No insurer licensed to carry on the business of insurance in this state that is required by law to contribute to or participate in, or that can be assessed by the Ohio insurance guaranty association pursuant to sections 3955.01 to 3955.19 of the Revised Code, or by the plan for apportionment of applicants for motor vehicle insurance pursuant to section 4509.70 of the Revised Code, or by the Ohio fair plan underwriting association pursuant to sections 3929.43 to 3929.61 of the Revised Code, or by the Ohio commercial insurance joint underwriting association pursuant to sections 3930.03 to 3930.18 of the Revised Code shall in any calendar year be required to contribute to, participate in, or be assessed by any one or more of those plans or associations in an amount or amounts totaling in excess of two and one-half per cent of its net direct Ohio premium volume for the year next preceding the year in which the assessment or assessments are made or the contributions or participations are required.
R.C. §3929.85