Glossary

Sub-Sublease

Also known as: sub-sublet

A further sublease of space by an existing subtenant to a third-party occupant, creating a fourth layer in the occupancy chain beneath the building owner, the original tenant (sublandlord), and the subtenant.

Sub-subleases became far more common as flexible-office operators and large corporate tenants both began subleasing excess space during periods of contraction, and each additional layer in the chain compounds the same structural risk present in any sublease — namely, that the sub-subtenant's right to occupy depends on the continued performance of every lease and sublease above it, none of which it is a party to. Master leases and first-level subleases increasingly restrict or flatly prohibit further sub-subleasing precisely because building owners want visibility into and some control over who ultimately occupies their property, for reasons ranging from security and insurance to preserving the building's tenant-mix positioning, so a proposed sub-sublease typically requires consent from both the building owner and the original sublandlord, not just the immediate subtenant's counterparty.