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
Pet-related deposit disputes usually turn on proof. In Wisconsin, landlords still need to handle the refund and deduction notice correctly, and renters usually ask whether the charge reflects actual damage or just the landlord's assumption that pets always create extra cost.
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