WHAT IS AN NNN LEASE

An NNN lease, short for triple net lease, is one point along a spectrum of commercial lease structures that allocate operating expense responsibility differently between landlord and tenant. Understanding where a specific lease falls on that spectrum, from a gross lease to a fully triple net lease, matters for accurately underwriting the net income a landlord will actually collect, since two properties with identical face rent can produce very different landlord cash flow depending on which expenses the tenant is responsible for reimbursing.

The lease spectrum: gross to triple net

Under a gross lease, the landlord pays all operating expenses, including property taxes, insurance, and maintenance, out of the rent collected, with the tenant paying only the stated rent amount. A modified gross lease shifts some expenses to the tenant, often utilities or a portion of common area maintenance, while the landlord retains responsibility for others, such as structural repairs. A single net lease, sometimes called an N lease, generally has the tenant paying property taxes in addition to rent, while a double net lease, or NN lease, adds building insurance to the tenant's responsibilities alongside taxes. A triple net lease, or NNN lease, extends the tenant's responsibility to include maintenance as well, leaving the landlord with responsibility generally limited to the building's structure and roof, depending on the specific lease language negotiated.

What structure and roof responsibility means in practice

Even in a triple net lease, the specific allocation of structural and roof responsibility varies by lease and deserves careful review before an investor relies on the NNN label alone. Some triple net leases are drafted as absolute net leases, sometimes called bondable leases, where the tenant assumes responsibility for the roof and structure as well, leaving the landlord with essentially no ongoing expense obligation for the life of the lease. Other triple net leases retain roof and structural responsibility with the landlord, which means a landlord should budget reserves for a roof replacement or structural repair even though taxes, insurance, and routine maintenance are the tenant's responsibility. Reading the actual lease language, rather than assuming every property marketed as NNN carries identical landlord obligations, is an important step before underwriting a specific candidate property.

Reimbursement mechanics

Triple net expenses are typically paid by the tenant either directly to the service provider or municipality, or reimbursed to the landlord after the landlord pays the expense and bills the tenant, depending on the lease's specific structure. Reimbursement leases require the landlord to front the expense and collect from the tenant, which introduces some collection risk if the tenant is slow to reimburse or disputes a charge, while direct-pay leases eliminate that intermediate step but require the landlord to confirm the tenant is actually staying current on taxes and insurance, since a lapse in insurance coverage or a delinquent tax bill ultimately remains the landlord's underlying property risk even under a triple net structure.

For a Boston, MA investor evaluating a candidate replacement property in a 1031 exchange, confirming exactly which expenses the tenant covers, how those expenses are collected, and who retains roof and structural responsibility should happen during lease review, well before the property is identified within the exchange's forty-five-day window. The site's Rent Roll Diligence service reviews these lease terms as part of a broader diligence process, and the Triple Net Lease (NNN) Investing explainer covers the broader underwriting and risk considerations for this asset category.