Ohio Revised Code Title LVII. Taxation § 5729.101

(A) When taxes levied by this chapter or by section 3737.71 of the Revised Code are assessed as the result of a tax return being filed late, the treasurer of state shall add interest to the taxes due. The interest shall accrue from the first day of the month following the last day on which the taxes were required to be paid had the assessment been certified by the date prescribed, to the last day of the month preceding the date on which the assessment was certified, and shall be computed on the basis of the taxes due.

(B) If an assessment has been certified pursuant to this chapter and an amended or final assessment is certified for the same taxpayer and the same tax year, the treasurer of state shall add interest to the deficiency or excess. The interest shall be computed on the excess or deficiency and shall accrue as follows: