The law in plain English
Return deadline
Under N.H. Rev. Stat. Sections 540-A:5 to 540-A:8; 540-B:10, the deposit response usually has to be sent within 30 days of the move-out timeline described by the state rule.
Required notice
New Hampshire generally caps the deposit at 1 month's rent or $100, whichever is greater, unless the landlord and tenant share facilities, and the landlord usually has 30 days to send the refund and itemized statement.
This dispute type
Once the New Hampshire 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 N.H. Rev. Stat. §§ 540-A:5 to 540-A:8; 540-B:10 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: You can recover double the deposit amount for any violation, plus attorney's fees; willful violations may add up to treble damages