The short answer
A gross lease has the tenant paying a flat rent while the landlord covers the building's operating costs, taxes, and insurance out of that rent. A net lease, most often seen as triple net or NNN, has the tenant paying base rent plus its pro rata share of property taxes, insurance, and common area maintenance separately from rent. A modified gross lease sits between the two, splitting specific expenses by negotiation rather than following either pattern wholesale. None of these labels has a fixed legal definition. What actually governs a tenancy is the lease's own expense, tax, and insurance clauses, so a deal marketed as triple net can still cap the tenant's exposure, and a lease called gross can still pass some costs through above a base year. The label sets an expectation; the clause sets the obligation.
What each label typically means
A full service or gross lease bundles operating costs into the rent the tenant pays. The landlord budgets for taxes, insurance, utilities, and maintenance and prices the rent to cover them, so the tenant sees one number and the landlord absorbs the risk if costs rise. Many gross leases still include an expense stop or a base year: the landlord covers costs up to that baseline, and the tenant reimburses the increase above it in later years, which means a gross lease is rarely as flat as the name implies once the term runs a few years.
A net lease shifts operating costs to the tenant, billed separately from base rent. Single net typically means the tenant pays property taxes on top of rent. Double net adds insurance. Triple net, the structure most common in retail and single-tenant industrial space, adds common area maintenance as well, so the tenant carries taxes, insurance, and CAM alongside a base rent that is set lower than a comparable gross lease would require, since the landlord is not pricing those costs into it.
A modified gross lease does not follow either pattern by default. The landlord and tenant negotiate which expenses the tenant reimburses and which the landlord absorbs, so two leases both called modified gross can allocate costs in different ways. The label tells you a split exists, not what it is.
The label is not the contract, the expense clause is
None of these terms are standardized by statute or industry body. A letter of intent that describes a deal as triple net is a starting expectation, not a binding allocation, and the lease that eventually gets signed can narrow it: a cap on CAM increases, an exclusion of capital repairs, or a landlord-absorbed administrative fee above a stated percentage all change what triple net means in that specific document. The reverse happens too, a lease marketed as gross can still pass through real estate tax increases above a base year, or bill separately for utilities that run outside normal business hours.
The only reliable way to know what a tenancy actually requires is to read the operating expense, tax, and insurance provisions themselves rather than relying on the header on page one or the name used during negotiation. Two leases in the same building, signed years apart, can carry the same label and different obligations if the expense language was renegotiated between them.
What changes operationally for the landlord
The lease structure drives what a landlord has to track and bill. Under a gross lease, the landlord owns the budgeting risk and needs to monitor whether actual costs are tracking the rent it set, since there is no annual reconciliation to true up a shortfall. Under a net lease, the landlord runs an annual reconciliation process, comparing estimated charges collected through the year against actual costs and billing or crediting the difference, the same mechanics covered in CAM reconciliation.
Net structures also add reporting obligations the landlord has to keep current: tenants with audit rights expect the underlying invoices to be available, and expense allocations have to be recalculated correctly whenever the mix of occupied and vacant space changes. A portfolio with a mix of gross, modified gross, and net leases across different tenants is really running two different administrative processes side by side, and confusing which tenancy follows which one is where billing errors start.
Common questions
Does triple net always mean the tenant pays every operating cost?
Not necessarily. Triple net describes the general pattern, taxes, insurance, and CAM billed to the tenant, but a specific lease can cap increases, exclude capital items, or leave certain costs with the landlord. The controlling document is the lease's own expense clause, not the triple net label.
Is a modified gross lease the same as a net lease with a discount?
No. Modified gross describes a negotiated split of specific expenses between landlord and tenant, and that split varies by lease. It is not a fixed midpoint between gross and net, so each modified gross lease has to be read on its own terms.
Can a lease change from gross to net, or the reverse, through an amendment?
Yes, if the amendment restates the expense provisions. Renewal terms sometimes shift the structure, converting a gross lease to net on renewal, for example, which means the expense clause has to be checked again at each renewal rather than assumed to carry forward unchanged.
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