Ohio Rev. Code § 5721.42
After the settlement required under division (C) of section 321.24 of the Revised Code, the county treasurer shall notify the certificate holder of the most recently issued tax certificate, by ordinary first class or certified mail or by binary means, that the certificate holder may purchase a subsequent tax certificate by paying all delinquent taxes on the related certificate parcel the lien against which has not been transferred by the sale of a tax certificate. During the thirty days after receiving the notice, the certificate holder possesses the exclusive right to purchase the subsequent tax certificate by paying those amounts to the county treasurer. The amount of the payment shall constitute a separate lien against the certificate parcel that shall be evidenced by the issuance by the treasurer to the certificate holder of an additional tax certificate with respect to the delinquent taxes so paid on the related certificate parcel. The amount of the payment as set forth in the tax certificate shall earn interest at the rate of eighteen per cent per year. The certificate period of each subsequent tax certificate shall terminate on the expiration date of the certificate period of the most recent tax certificate for the same certificate parcel.
R.C. § 5721.42