The law in plain English
Return deadline
Under Wis. Admin. Code ATCP 134.04, 134.06; Wis. Stat. Section 704.28, the deposit response usually has to be sent within 21 days of the move-out timeline described by the state rule.
Required notice
Wisconsin generally requires the refund or a written itemized statement within 21 days, and tenants usually preserve a written demand before suing for double damages.
This dispute type
Once the Wisconsin 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 Wis. Admin. Code ATCP 134.04, 134.06; Wis. Stat. § 704.28 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: Double the amount wrongfully withheld, plus court costs and reasonable attorney fees