The law in plain English
Return deadline
Under Mass. Gen. Laws ch. 186, Section 15B, the deposit response usually has to be sent within 30 days of the move-out timeline described by the state rule.
Required notice
Massachusetts generally gives the landlord 30 days to return the deposit or send a compliant itemized statement, and statutory violations can trigger mandatory treble damages.
This dispute type
Pet-related deposit disputes usually turn on proof. In Massachusetts, 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: 3x the deposit, plus interest, court costs, and reasonable attorney's fees