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 Pennsylvania, the Landlord and Tenant Act of 1951 regulates security deposits for residential leases. The law stipulates that for the first year of renting, a landlord may not require a security deposit of more than two months' rent. After the first year, the maximum security deposit that can be required is reduced to one month's rent. Additionally, if a tenant has occupied the property for more than five years, the landlord must place any security deposit over $100 in an interest-bearing bank account, and the tenant is entitled to the interest earned. Upon termination of the lease, the landlord has 30 days to return the security deposit or provide a written list of damages and the cost of repairs, which are to be deducted from the security deposit. This list must be delivered to the tenant along with any remaining portion of the security deposit. If the landlord fails to comply with these requirements, they may be liable for up to twice the amount of the security deposit withheld.