Subleasing occurs when the current tenant or tenants (who signed the lease with the landlord) attempt to rent or lease some or all of the leased premises to a new tenant or tenants. This practice is also known as subletting and the new lease to a new tenant or tenants may be referred to as a sublease or a sublet.

Subleasing may be done under a residential or a commercial lease agreement, when permitted by the original lease agreement and by law.

Subleasing may or may not be permitted by the terms of the original lease, and when it is permitted, it is often only permitted with the prior written agreement of the landlord, who wants to screen the proposed new tenants and know the identities of the persons occupying the leased premises.

A tenant who sublets the leased premises, in whole or in part, generally remains liable for the rent due and for any damage caused by the new tenant or tenants. This is because the new tenant’s contract is with the original tenant—not with the landlord. And the original tenant’s contract with the landlord obligates the original tenant to pay the full rent to the landlord on time and to be responsible for any damage done to the leased premises (other than ordinary wear and tear).

It is also important for the original tenant and the landlord to consider security deposit issues, as any tenant or tenants leaving the leased premises may want the return of their portion of the security deposit—and if the landlord agrees to return those security deposit funds the landlord may want to replace them with security deposit funds from the new subtenant or subtenants.

If the original tenant does not want to continue to be liable on the lease, the original tenant might ask the landlord to agree to terminate the lease and enter into a new lease with the new tenant or tenants—rather than the original tenant subleasing to the new tenant or tenants.

Laws vary from state to state and state statutes and city and municipal codes and ordinances may permit, restrict, or prohibit subleasing. In some cities a tenant may have the right to sublease even if the lease agreement prohibits subleasing—which is usually the result of a city or municipal code or ordinance that effectively makes the tenant’s right to sublease a right that cannot be waived by contract.

And under some city codes or ordinances the tenant has the right to replace a roommate as long as the new roommate meets the landlord’s screening standards.

In New Hampshire, subleasing is a practice where the original tenant rents out the leased property to a new tenant. Whether subleasing is allowed depends on the terms of the original lease agreement and state law. Typically, the original lease must explicitly permit subleasing, and even then, the landlord's prior written consent is often required. The landlord may want to screen the new tenant to ensure they meet certain standards. The original tenant remains responsible for rent and any damages caused by the subtenant, as their agreement with the landlord still stands. Security deposit arrangements must also be considered, as departing tenants may seek the return of their deposits, which the landlord may wish to replace with funds from the subtenant. If the original tenant wishes to be released from their obligations, they may negotiate with the landlord to terminate the existing lease and have the landlord enter into a new lease with the new tenant. New Hampshire law does not have specific statutes overriding lease provisions regarding subleasing, so the terms of the lease and mutual agreements between the landlord and tenant typically govern the permissibility and conditions of subleasing.