Angel Campa, FounderTriple net leases (NNN leases) are the dominant structure for single-tenant commercial real estate and net lease investment properties. Understanding how NNN leases work — what expenses pass through, how they compare to gross leases, and how to calculate total occupancy cost — is foundational knowledge for anyone buying, selling, or occupying commercial real estate.
What Is a Triple Net Lease?
A triple net lease is a commercial lease structure in which the tenant pays base rent plus three categories of operating expenses: property taxes, building insurance, and maintenance and repairs. The "triple" refers to these three net expense categories — each passes through to the tenant in addition to base rent. Because the landlord receives base rent with minimal operating expense exposure, triple net leases are the preferred structure for passive real estate investors and institutional net lease portfolios.
Triple net leases are common in single-tenant retail properties (drugstores, fast food, dollar stores), industrial facilities, and net lease investment properties. In multi-tenant buildings, the NNN structure typically applies through CAM charges — the proportional allocation of building operating expenses across tenants. A pure single-tenant NNN lease allocates 100% of all operating expenses to the sole tenant.
How Does a Triple Net Lease Work?
In a triple net lease, the landlord charges a lower base rent that reflects the tenant's obligation to cover operating expenses directly. The mechanics work in three components:
Base rent. The landlord charges a base rent per rentable square foot per year — typically lower than a comparable gross lease by an amount approximating the NNN expense load. If a gross lease in a given market would command $30/SF, a comparable NNN lease might carry a base rent of $18–$22/SF, with the $8–$12 difference representing the expected NNN expense passthrough.
Estimated NNN payments. At the start of each year, the landlord provides an estimate of the property tax, insurance, and CAM expenses for the year. The tenant pays these estimated amounts monthly as separate line items alongside base rent. For a multi-tenant building, each tenant pays their pro-rata share based on rentable square footage.
Annual reconciliation. After year-end, the landlord calculates actual expenses and compares them to the estimates collected. If actual expenses exceeded estimates, the tenant owes a true-up payment. If actual expenses were lower, the tenant receives a credit toward future NNN payments or a cash refund. The reconciliation statement should arrive within 90–120 days of year-end; most leases specify a deadline.
What Is Included in a Triple Net Lease?
A triple net lease includes three expense categories beyond base rent. The specific definitions matter — what qualifies as a covered expense is determined by the lease, not by the general NNN concept.
Property taxes. The tenant pays their proportional share of real estate taxes assessed on the property. For single-tenant buildings, the tenant typically pays 100% of taxes. For multi-tenant buildings, each tenant pays their pro-rata share. Property tax escalation can significantly affect total occupancy cost in markets with frequent reassessments — a tenant who signed a NNN lease in a flat-tax market may face 15–30% property tax increases in years two and three following a reassessment.
Building insurance. The tenant pays their share of the landlord's property and casualty insurance premiums, including building coverage, general liability, and sometimes umbrella coverage. The tenant typically carries their own liability insurance separately and names the landlord as an additional insured. Insurance premiums have risen significantly in coastal markets — tenants in hurricane or wildfire-exposed locations should model insurance cost scenarios before signing a long-term NNN lease.
Maintenance and repairs (CAM). This is the broadest and most negotiated component. In a well-drafted NNN lease, CAM covers common area maintenance — parking lot maintenance, landscaping, exterior lighting, janitorial for shared spaces, and routine repairs to building systems. In a less favorable NNN lease, CAM may also include capital expenditures like roof replacement and HVAC system overhaul. The difference between these definitions can be $5–$15 per square foot per year on a heavily maintained property.
For a detailed breakdown of CAM definitions, caps, and negotiation, see CAM charges explained.
Triple Net Lease vs. Gross Lease
Triple net leases and gross leases represent opposite ends of the expense allocation spectrum. The right structure depends on which party is better positioned to manage operating expense variability.
| Feature | Triple Net Lease (NNN) | Gross Lease |
|---|---|---|
| Base rent | Lower | Higher |
| Tenant pays | Base rent + taxes + insurance + maintenance | Base rent only |
| Total cost predictability | Variable (fluctuates with actual expenses) | Fixed (or with defined escalations) |
| Expense risk | Tenant | Landlord |
| Landlord net income | Predictable, near-passive | Variable (absorbs expense fluctuations) |
| Best for tenant | Tenant who can manage/control operating costs | Tenant who needs budget predictability |
| Best for landlord | Landlord seeking passive income | Landlord with confidence in expense management |
Modified gross leases sit between these structures. The tenant pays a base rent that includes some expense categories (often property taxes and insurance) but not others (maintenance passes through separately). Base year gross leases are a common variant: the landlord covers expenses up to the base year level, and the tenant pays any increases above that base — combining the predictability of a gross lease with the expense-sharing of an NNN lease for expense growth above the base.
Triple Net Lease Calculator
Use this formula to estimate total annual NNN occupancy cost:
Annual total cost = (Base rent/SF + Property tax/SF + Insurance/SF + CAM/SF) × Rentable SF
Example — 5,000 SF retail tenant:
- Base rent: $22.00/SF/year
- Property taxes: $3.50/SF/year
- Insurance: $1.50/SF/year
- CAM: $5.00/SF/year
- Total: $32.00/SF × 5,000 SF = $160,000/year ($13,333/month)
Effective gross rent equivalent: $32.00/SF NNN is economically equivalent to a $32.00/SF gross lease — not the $22.00/SF base rent. When comparing NNN and gross lease proposals, always convert to total occupancy cost per square foot before comparing.
Modeling expense escalation: NNN expenses are not fixed. Property taxes can increase 5–20% in reassessment years. Insurance premiums in CAT-exposed markets have risen 25–50% since 2020. CAM with a 3% annual cap grows 34% over a 10-year lease. For a 10-year NNN lease, model a range of expense scenarios — base, moderate escalation, and stress — to understand total occupancy cost at expiration.
Pros and Cons for Tenants
Advantages of NNN leases for tenants:
- Lower base rent than comparable gross leases
- Direct control over maintenance quality — the tenant who maintains the space well may spend less than a landlord managing remotely
- Transparency into actual operating costs with annual reconciliation statements
- Typically longer initial terms with renewal options — NNN leases often run 10–25 years with 5-year renewal options
Disadvantages of NNN leases for tenants:
- Total occupancy cost is variable and can increase significantly if property taxes or insurance spike
- CAM definitions without expense caps can expose tenants to unlimited operating expense growth
- Capital expenditure risk if the lease does not exclude roof, HVAC, and structural costs from the tenant's obligations
- Annual reconciliation creates cash flow uncertainty — a large true-up payment may arrive 4–5 months into the following year
The most important protections to negotiate in a NNN lease: CAM cap (3–5% annually on controllable expenses), capital expenditure exclusion, audit rights, and a reconciliation deadline with a landlord penalty for late delivery.
Pros and Cons for Landlords
Advantages of NNN leases for landlords:
- Near-passive income stream — the landlord receives base rent with minimal ongoing expense management
- Long-term leases with creditworthy tenants (national chains, franchises) create predictable cash flows attractive for institutional investors
- Operating expense increases pass through to tenants rather than compressing net operating income
- NNN properties with long lease terms and investment-grade tenants trade at cap rates reflecting their bond-like income characteristics
Disadvantages of NNN leases for landlords:
- Tenant has control over property maintenance; deferred maintenance can reduce property value without immediate income impact
- Long-term leases lock in below-market rents if the market appreciates faster than the escalation schedule
- Tenant default on a long NNN lease — especially a single-tenant property — creates concentrated vacancy risk with a specialized building that may be difficult to re-tenant
For abstracting NNN lease data — extracting CAM caps, expense definitions, reconciliation deadlines, and audit rights into structured fields — Lextract processes NNN leases in 5–15 minutes and flags provisions that create tenant risk: uncapped CAM, missing audit rights, and capital expenditure pass-throughs. See what is lease abstraction for how the extraction process works.