The most consequential decision in any commercial lease negotiation is not the base rent -- it is who pays the expenses on top of it. Two tenants can sign leases with identical base rents and end up with wildly different total occupancy costs depending on the lease structure. Understanding the difference between NNN and gross leases is the foundation of any serious lease review.
What a Triple Net (NNN) Lease Actually Means
In a triple net lease, the tenant pays three costs beyond base rent: property taxes, property insurance, and maintenance costs for the building. The name comes from these three "nets" that pass through from landlord to tenant.
In practice, NNN leases often include considerably more than those three buckets. Common area maintenance (CAM) charges in an NNN lease can encompass landscaping, parking lot repairs, snow removal, exterior lighting, security, janitorial services for shared areas, property management fees, and administrative charges. The base rent figure in an NNN lease is typically lower than a gross lease for the same space precisely because the tenant absorbs these variable costs.
The financial exposure is real. In a retail or industrial NNN lease, CAM charges of $4 to $8 per square foot per year on top of base rent are not unusual. A 5,000-square-foot tenant paying $20 NNN with $6 in annual CAM is actually paying $26 per square foot in total occupancy cost -- 30% more than the base rent implies.
What a Full-Service Gross Lease Actually Means
In a full-service gross lease, the landlord bundles all operating expenses into a single rental rate. The tenant writes one check and the landlord manages taxes, insurance, and building operating costs from that revenue. This structure is most common in multi-tenant office buildings where separating individual tenant contributions to shared expenses is administratively complex.
The gross rate is always higher than a comparable NNN base rent because the landlord is pricing in expected expenses and adding a margin for uncertainty. The tenant trades expense variability for predictability.
Most "gross" leases are not truly full-service. They contain an expense stop -- a dollar-per-square-foot threshold above which additional operating expenses pass through to the tenant. The stop is typically set at the operating expense level in the base year of the lease. If expenses rise above the stop, the tenant pays the overage proportionally. This converts what looks like a fixed-cost lease into a partially variable one.
Modified Gross: The Middle Ground
Modified gross leases split the difference. The tenant pays base rent plus some defined subset of operating expenses -- often utilities and janitorial services -- while the landlord covers taxes, insurance, and structural maintenance. The specific split varies by market, property type, and negotiation.
Modified gross is common in flex industrial, suburban office, and mixed-use properties. The key is to read the lease carefully rather than rely on the label. "Modified gross" means nothing standardized; the only thing that matters is the specific list of inclusions and exclusions in the operating expense clause.
Which Structure Is Better for Tenants
There is no universally correct answer. The right structure depends on your negotiating position, the stability of the property, and your tolerance for expense variability.
NNN leases favor tenants who are confident the property is well-managed, who have audit rights to verify expense allocations, and who are negotiating from a position of strength (i.e., the landlord needs them more than they need the space). A creditworthy, long-term tenant often gets favorable NNN terms precisely because the landlord values the stability.
Gross leases favor tenants who prioritize budget certainty over potential savings. A startup with tight cash flow management may find the predictability of a gross rate worth the premium. The downside is that if the landlord manages expenses efficiently, the tenant is paying for margin they did not need.
The practical test: if you cannot get a CAM cap and cannot get audit rights in an NNN lease, a gross lease with a modest expense stop may be the better deal even if the face rate is higher.
Fields to Extract for Each Lease Structure
A proper lease abstract flags the structure immediately and then extracts the fields that determine true cost exposure.
For NNN leases, the critical fields are:
- CAM cap percentage (controllable expense cap, typically 3-5% annually)
- Base year or estimated CAM figure at lease commencement
- Management fee percentage (should be capped, typically at 5% of collected rents)
- Excluded expenses list (capital expenditures, above-grade roof, structural repairs)
- Gross-up provision language (whether occupancy is grossed up and to what percentage)
- Audit rights clause (notice window, frequency, what records the tenant can inspect)
- Reconciliation timing (when annual true-up statements are delivered)
For gross leases, the critical fields are:
- Expense stop amount (dollars per square foot)
- Base year designation
- Operating expense definition (what is included in the controllable/uncontrollable split)
- Utility exclusions (electricity often passes through even in gross leases)
Red Flags in NNN Leases
Uncapped CAM is the most common and most consequential red flag in NNN leases. Without a cap on controllable expense increases, a tenant has no limit on how much annual CAM growth they absorb. Landlords who push back on caps are signaling either poor expense management or capital expenditure plans the tenant should know about.
Gross-up provisions deserve careful reading. These clauses allow the landlord to calculate operating expenses as if the building were 90% or 95% occupied, regardless of actual occupancy. The effect is that a tenant in a partially occupied building pays as if the building were full. Gross-up provisions are standard in many markets, but the occupancy threshold matters -- 90% gross-up is more favorable to tenants than 95%.
No audit rights is a serious problem. Without the ability to inspect expense records, there is no mechanism to challenge incorrect allocations. Management fees, administrative charges, and expenses that should be excluded from CAM regularly show up in reconciliation statements. Audit rights, even if you never exercise them, change landlord behavior.
Admin and overhead charges above 15% of CAM are worth flagging. Some leases allow landlords to add an administrative fee on top of a management fee, effectively double-charging for building management costs.
When you are reviewing a commercial lease abstract before signing or acquiring a property, these are the fields that determine whether the economics match the headline rent. Upload your lease to Lextract to extract all 125+ fields and get a red flag report before you sign.