A triple net lease — almost always written as NNN — is a commercial lease where the tenant pays base rent plus their pro-rata share of the landlord's property taxes, property insurance, and common area maintenance (CAM). Those three "nets" are where the name comes from, and where most of the surprises come from too. The rent number a landlord quotes on a NNN deal is never what the tenant actually pays. The real number is base rent plus the pass-throughs, and the pass-throughs are often larger than new tenants expect.
This is a plain-English guide to what a triple net lease actually covers, how to read the quoted rate, what the math looks like on a real deal, and the clauses that determine whether the NNN structure is fair or quietly abusive.
What "Triple Net" Means in a Commercial Lease
In any commercial lease, someone has to pay the building's operating costs. The question is who, and how. There are three common structures:
- Full-service gross (FSG). Tenant pays one all-in number. Landlord covers taxes, insurance, maintenance, utilities, janitorial. Common in high-end office towers.
- Modified gross. Tenant pays base rent plus some expenses, usually with a base year stop — the landlord eats expenses up to a set amount, and the tenant pays increases above that.
- Triple net (NNN). Tenant pays base rent plus their pro-rata share of three categories: real estate taxes, property insurance, and CAM. The tenant is effectively an owner-operator of their slice of the building.
Retail leases are almost always NNN. Industrial is usually NNN. Multi-tenant office is sometimes NNN, sometimes modified gross. Single-tenant office — a full building leased to one company — is often absolute NNN, where the tenant pays everything including roof and structure.
Absolute NNN and standard NNN are not the same. In a standard NNN, the landlord usually keeps responsibility for the roof, structural walls, and foundations. In absolute NNN, those are on the tenant too. For any long-term single-tenant deal, make sure the letter of intent and the lease are clear about which one applies.
How to Read a Quoted NNN Rate
When a broker says "$30 NNN," they usually mean $30 per rentable square foot per year in base rent, with the three nets on top. The nets get quoted separately — sometimes as a single combined number like "$8.50 NNN estimate," sometimes as three line items.
Here is what $30 NNN actually costs a 3,000 sf tenant:
- Base rent: 3,000 sf × $30 = $90,000/year
- Taxes (N1): 3,000 × $4.00 = $12,000/year
- Insurance (N2): 3,000 × $1.00 = $3,000/year
- CAM (N3): 3,000 × $6.00 = $18,000/year
- Total occupancy: $123,000/year, or $41 per square foot all-in
The quoted rate was $30. The real rate is $41 — a 37% markup that does not appear in the first conversation. New tenants see $30 and budget $90,000. Experienced tenants always ask two questions the first time they hear a NNN quote: "what are the current NNN charges?" and "can I see a year of actual bills?"
What CAM Actually Covers
Taxes and insurance are straightforward — property tax bills and property insurance premiums, divided by the building's rentable square footage, multiplied by yours. CAM is where the ambiguity lives.
Common area maintenance is everything the landlord spends to run the shared parts of the property. In a shopping center, that means the parking lot, landscaping, lighting, security, trash, shared utilities, property management fees, and a long tail of smaller items. In a multi-tenant office, it also includes lobby, hallways, elevators, and restrooms.
The lease will define CAM in a paragraph that looks thorough. It usually is not. Common line items worth looking for — and redlining out if the landlord will accept it:
- Capital improvements. New roof, new parking lot, new HVAC system. These are landlord investments, not operating expenses. Standard redline excludes capital items or allows them only if amortized over useful life and required by law.
- Management fees above market. Reasonable is 3-5% of gross rent. Anything above 5% or 15% of CAM is worth pushing back on.
- Marketing and promotion. If the landlord has a marketing fund for the center, it should be a separate line item the tenant can opt into, not buried in CAM.
- Administrative fees. A flat 10-15% admin markup on top of CAM is common and usually negotiable down or out.
- Reserves for future expenses. Landlords sometimes charge a reserve for future repairs. If the reserve is not actually spent, it should be refunded or credited.
- Leasing commissions and legal fees for other tenants. Not yours. Should be excluded.
Every serious tenant redline on a NNN lease spends most of its ink on the operating expense definition. For more on how that redline actually runs, see our commercial lease redlining guide.
The Audit Right
The single most important clause in any NNN lease is the tenant's audit right — the right to inspect the landlord's books once a year, at the tenant's expense, to verify that the CAM charges actually match what the lease allows the landlord to pass through.
A reasonable audit clause includes:
- The right to audit within twelve to twenty-four months of receiving the annual CAM reconciliation
- A requirement that the landlord provide supporting documentation (invoices, tax bills, insurance policies)
- A provision that if overcharges exceed a threshold (usually 3-5%), the landlord reimburses the tenant's audit costs
- No confidentiality clause that prevents the tenant from comparing notes with other tenants in the center
Landlord first drafts often strip the audit right out, or limit it to ninety days after the reconciliation with no documentation requirement. That is not an audit right — that is a permission slip. Redline it.
How NNN Escalates Over Time
A NNN lease has two escalation engines running in parallel. The first is base rent escalation, which is negotiated — typically 3% per year, or CPI with a floor and cap, or fixed bumps at specified years. The second is NNN escalation, which is not really negotiated — it is whatever the actual taxes, insurance, and CAM add up to each year.
NNN charges tend to grow faster than inflation. Property taxes reset on reassessment. Insurance premiums have moved sharply in certain markets — Florida, California, coastal Texas. CAM creeps up with labor, utilities, and deferred maintenance. According to IRS guidance on commercial rental expenses, these are the three cost categories most property owners pass through to tenants precisely because they are volatile.
Over a ten-year term, it is not unusual to see NNN charges grow 40-60% even when base rent grows 30%. A tenant modeling a NNN deal should build separate escalation assumptions for base rent and for each of the three nets, not a single blended rent-growth number.
Clauses to Negotiate Around the NNN Structure
Even once the NNN structure is accepted, a few clauses can make it materially more tenant-friendly:
- CAM caps. A cap on the annual increase in controllable CAM — usually 5% per year, compounding or non-compounding. "Controllable" excludes taxes, insurance, snow removal, and utilities. This is the single highest-value tenant concession on a retail NNN lease.
- Exclusions at signing. Before the lease is signed, ask for a list of exclusions to be spelled out in the operating expense definition, not just referenced generically.
- Gross-up provisions. If the building is not fully leased, CAM per square foot looks artificially low. The landlord will want to "gross up" occupancy-variable expenses to 95% occupancy. Tenants should agree only for occupancy-variable items (janitorial, utilities) — not fixed costs like taxes.
- Base year reset. In a modified gross or gross-with-NNN-escalations lease, make sure the base year is a normal year, not a year with known one-time expenses that will inflate the baseline.
For any NNN lease you are about to sign, running the full document through our Lease Reader will surface the operating expense definition, audit language, and escalation mechanics in plain English before you get to the attorney call. And for NNN leases the landlord sends as a counter, the Redline Analyzer will flag what quietly changed in the definition of operating expenses between drafts.
Before You Sign a NNN Lease
Three final checks:
- Ask for three years of actual CAM reconciliations for the property, not just the current estimate. If the landlord will not provide them, assume charges will run at the high end of the historical range.
- Model the total occupancy cost across the full term, including the NNN escalation. Compare against your revenue forecast, not your current revenue.
- Get the operating expense definition right in round one of the redline. Everything else follows from there.
A NNN lease is not bad — it is the dominant structure in retail and industrial for good reasons. But it only works for the tenant if the definitions and audit rights are tight. The quoted rent is the conversation starter. The real lease is the next ten pages.
This article is educational, not legal or tax advice — always work with a commercial real estate attorney before signing any lease, and a CPA on tax treatment. For a plain-English read of a specific NNN lease, try the Lease Reader. To understand what changes between rounds of landlord counters, use the Redline Analyzer. And for background on the document that precedes the lease, see our commercial LOI guide.