The law in plain English
Return deadline
Under Wash. Rev. Code Sections 59.18.260 to 59.18.285; 59.18.610; 59.18.670, the deposit response usually has to be sent within 30 days of the move-out timeline described by the state rule.
Required notice
Washington generally requires the refund or an itemized deduction statement with supporting receipts within 30 days.
This dispute type
Once the Washington 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 Wash. Rev. Code §§ 59.18.260 to 59.18.285; 59.18.610; 59.18.670 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: Up to 2x the deposit, plus court costs and reasonable attorney's fees