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
In Wisconsin, renters usually challenge deposit deductions for scuffs, faded paint, flattened carpet, and similar aging because those issues look more like ordinary use than repairable damage. The statute still controls when the refund had to be sent and how deductions had to be explained.
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