Does a Ohio landlord owe interest on the security deposit?

It depends on the state and the locality. Some Ohio jurisdictions require landlords to pay interest on security deposits at a rate set by statute (typically 0.5 percent to 4 percent annually), with the interest paid annually, at lease renewal, or at move-out. Other Ohio jurisdictions require interest only if the deposit is held longer than a defined period (often one year) or only on multi-unit buildings (5+ units in some statutes). The interest must be tracked in a separate accounting. Failure to pay required interest can compound the deposit-return penalty: the unpaid interest itself is owed, plus any state-specific damages. Up to 2x the wrongfully withheld amount plus attorney fees under ORC 5321.16(C) if the landlord acts in bad faith. If your state requires interest, document it in the lease and the move-out itemized statement.

Source: ORC 5321.16