underlet

To underlet means to sublet or rent out property that you yourself are currently leasing from a landlord. It is more formal than simply letting a friend crash on your couch; it involves a secondary rental arrangement where another person becomes an "under-tenant," paying rent for a specific portion of the space.

The term is frequently used in the context of commercial properties—for instance, a large firm might underlet a spare wing of their office to a smaller business. However, it is also common in residential rentals. For example: "The landlord agreed to allow her to underlet the spare bedroom while she was studying abroad." It is crucial to understand that underletting almost always requires written consent from the original landlord; doing so without permission is typically a major breach of the primary lease.

Think of the process in layers: The landlord leases the property to you, and then you lease (or underlet) a part of it to someone else. Unlike "assigning" a lease, where you walk away and hand the contract to a new person, when you underlet, you remain legally responsible for the entire property and the total rent due to the owner. While the word is rooted in older English legal terminology, it remains a precise way to describe the subordinate nature of these secondary rental agreements. Whether you are a business owner with extra floor space or a renter with a spare room, underletting is the formal path to sharing your space and your costs.