The law in plain English
Return deadline
Under Idaho Code Section 6-321, the deposit response usually has to be sent within 30 days of the move-out timeline described by the state rule.
Required notice
Idaho generally does not impose a statewide deposit cap, and the landlord usually has 21 days by default, or up to 30 days if the lease says so, to send the refund and itemized statement.
This dispute type
Once the Idaho 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 Idaho Code § 6-321 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 any portion; you can recover up to treble (3x) damages, plus court costs and attorney's fees per Idaho Code § 6-320