The law in plain English
Return deadline
Under Iowa Code Section 562A.12, the deposit response usually has to be sent within 30 days of the move-out timeline described by the state rule.
Required notice
Iowa generally caps the deposit at 2 months' rent, and the landlord usually has 30 days after termination and receipt of the forwarding address to send an itemized statement and refund or risk forfeiture and double-damages exposure.
This dispute type
Once the Iowa deadline passes, the dispute stops being only about the deductions and becomes a deadline-compliance problem too. A landlord may still argue damage existed, but Iowa Code § 562A.12 sets the clock for returning the balance and explaining any amount withheld.
Penalty leverage
If the withholding was wrongful or in bad faith, the exposure allowed under the statute is: Landlord forfeits the right to retain; you can recover up to twice the amount wrongfully withheld as damages