Most residential landlords require tenants to pay a security deposit to cover any repairs needed when the tenant moves out, or to cover the tenant’s failure to pay the last month's rent.

Laws vary from state to state, but many states have statutes that provide the maximum amount of security deposit a landlord may require for a residential lease and the costs for which the landlord may use the security deposit (cleaning, repairs, unpaid rent) following termination of the lease.

These laws also provide a specific deadline (often 30-60 days) for the landlord to return the tenant’s security deposit following termination of the lease—after deducting any amount properly withheld, as allowed by law.

In New Hampshire, landlords can require tenants to pay a security deposit, which is regulated under state law. The maximum amount a landlord can charge for a security deposit is one month's rent or $100, whichever is greater, as per RSA 540-A:6. The security deposit can be used to cover the costs of repairs for damage beyond normal wear and tear, cleaning, unpaid rent, or other breaches of the lease agreement. After the termination of the lease, New Hampshire law requires landlords to return the security deposit within 30 days. If the landlord withholds any portion of the deposit, they must provide the tenant with a written, itemized list of deductions. Failure to comply with these regulations can result in the landlord being liable to the tenant for damages, as well as potential penalties.