When you see a commercial space advertised at "$20 per square foot NNN," you might think you've found a great deal. After all, similar spaces in the area are listed at $28 per square foot on a full-service basis. But that $20 NNN rate is only the beginning of your cost. The three N's — representing property taxes, insurance, and maintenance — can add $8 to $15 per square foot to your annual cost, potentially making that "bargain" lease more expensive than the full-service alternative.
Triple net leases are the dominant lease structure in commercial real estate, particularly for retail, industrial, and single-tenant properties. Understanding how they work — and what to watch for — is essential for managing your total tenant exposure.
What Does "Triple Net" Actually Mean?
A triple net lease (abbreviated NNN) is a lease structure in which the tenant pays three categories of property operating expenses in addition to the base rent:
- Property taxes — the real estate taxes assessed by the local government on the property.
- Property insurance — the landlord's insurance premiums for the building (fire, liability, casualty). Note: you'll also need your own tenant's insurance policy.
- Common area maintenance (CAM) — the costs of maintaining and operating the property's common areas, which can include landscaping, parking lot maintenance, snow removal, trash collection, shared HVAC systems, elevator maintenance, security, management fees, and more.
These three expense categories are collectively referred to as "operating expenses," "additional rent," or "NNN charges." They're billed to you monthly (usually as estimated amounts) and reconciled annually against the landlord's actual costs.
The key takeaway: When a lease is quoted as "NNN," the dollar-per-square-foot rate you see is the base rent only. Your actual occupancy cost is the base rent plus your proportionate share of taxes, insurance, and CAM.
Lease Structure Comparison
Understanding where NNN falls on the spectrum of lease structures helps you evaluate different properties on an apples-to-apples basis.
| Lease Type | Tenant Pays | Landlord Pays |
|---|---|---|
| Full Service (Gross) | One all-inclusive rent amount | All operating expenses (taxes, insurance, maintenance, utilities, janitorial) |
| Modified Gross | Base rent + some expenses (varies by lease) | Some operating expenses — negotiated on a deal-by-deal basis |
| Triple Net (NNN) | Base rent + property taxes + insurance + CAM | Structural repairs (roof, foundation) — sometimes |
| Absolute Net | Base rent + ALL expenses including structural | Nothing — tenant bears all costs including roof and structure |
How CAM Charges Are Calculated
CAM (Common Area Maintenance) charges are the most complex and frequently disputed component of NNN leases. Here's how they typically work:
Pro-Rata Share
Your share of operating expenses is calculated based on your proportionate share of the building or property. This is usually expressed as a percentage: the square footage of your leased space divided by the total leasable square footage of the property.
For example, if you lease 2,000 square feet in a 50,000-square-foot shopping center, your pro-rata share is 4%. If the property's total annual CAM expenses are $200,000, your share would be $8,000 per year, or approximately $667 per month.
What Gets Included in CAM
This is where the details matter enormously. A broadly defined CAM provision can include expenses you wouldn't expect:
- Standard items: Landscaping, parking lot maintenance and resurfacing, exterior lighting, snow removal, trash collection, shared utility costs, common area cleaning, security, fire system maintenance.
- Potentially problematic items: Property management fees (typically 3–8% of gross rent collected), landlord's administrative costs, capital improvements amortized over their useful life, marketing and promotional costs (in retail centers), legal and accounting fees for operating the property.
- Items that should be excluded: Repairs covered by insurance, costs of correcting building code violations that predate your tenancy, depreciation, mortgage payments, landlord's income taxes, costs of leasing to other tenants (commissions, tenant improvements), costs attributable to other tenants' specific requirements.
Watch out for management fees. A 5% management fee applied to gross rents sounds small, but on a property collecting $2 million in rent annually, that's $100,000 — and you're paying your pro-rata share of it. On a 4% share, that's $4,000/year in management fees alone, billed to you as CAM.
Estimated vs. Actual Costs
Most NNN leases require you to pay estimated monthly amounts based on the landlord's projection of annual expenses. At the end of each calendar year, the landlord performs a reconciliation (sometimes called a "true-up") comparing the estimated amounts you paid against the actual expenses incurred.
If actual expenses exceeded estimates, you receive a bill for the difference. If estimates exceeded actuals, you receive a credit (though some leases only apply credits against future payments rather than issuing refunds). Year-over-year increases of 5–10% in CAM charges are common, and significant jumps can occur when major maintenance is performed or property taxes are reassessed.
The Real Cost: Why NNN Is Often More Expensive Than You Think
Let's look at a concrete example. Consider a 2,500-square-foot retail space in a suburban shopping center:
| Cost Component | Per Sq Ft/Year | Annual Cost | Monthly Cost |
|---|---|---|---|
| Base rent | $22.00 | $55,000 | $4,583 |
| Property taxes | $4.50 | $11,250 | $938 |
| Insurance | $1.25 | $3,125 | $260 |
| CAM charges | $5.75 | $14,375 | $1,198 |
| Total occupancy cost | $33.50 | $83,750 | $6,979 |
In this example, the NNN charges ($11.50/sq ft) add 52% to the base rent. Your actual monthly cost is $6,979 — not the $4,583 suggested by the base rent alone. This is why comparing NNN leases to full-service leases requires converting everything to a "total occupancy cost" basis.
What to Watch For in NNN Leases
CAM Caps
A CAM cap limits the maximum amount your CAM charges can increase year over year. A typical cap is 3–5% annually. Without a cap, a major expense (parking lot resurfacing, roof replacement, elevator overhaul) can cause your CAM to spike dramatically in a single year. Caps are one of the most important provisions to negotiate.
Be aware of the distinction between cumulative and non-cumulative (compounding) caps. A cumulative cap means unused portions carry forward. A 5% annual cap on a $10/sq ft starting CAM means year-two CAM can't exceed $10.50 regardless of actual costs — and if year-two actual was only $10.20, the landlord can't "bank" that unused $0.30 for future increases. A compounding cap allows the increase to compound annually.
CAM Exclusions
Negotiate specific exclusions from CAM charges. Items commonly negotiated for exclusion include:
- Capital improvements (or require them to be amortized over useful life, not expensed immediately)
- Costs reimbursed by insurance
- Costs attributable to other specific tenants
- Marketing and promotional expenses
- Legal fees for disputes with other tenants or government entities
- Costs of correcting latent defects or code violations
Audit Rights
Insist on the right to audit the landlord's books with respect to operating expenses. This means you (or your accountant) can review the landlord's actual expense records to verify that the charges billed to you are accurate, properly allocated, and consistent with the lease terms. Many tenants never exercise this right, but audits frequently uncover overcharges, misallocated expenses, and costs that should have been excluded.
A good audit provision includes: the right to audit within a reasonable period after receiving the annual reconciliation (typically 60–120 days), the landlord's obligation to maintain records for at least 3 years, and a provision that the landlord reimburses your audit costs if the audit reveals an overcharge exceeding a specified threshold (commonly 3–5%).
Base Year vs. Fixed Stops
Some NNN leases use a base year approach: you pay operating expenses only to the extent they exceed a "base year" amount (typically the first year of your lease). This gives you cost certainty for year one and limits your exposure to increases in subsequent years. A fixed stop is similar but uses a specific dollar amount rather than actual first-year costs.
How to Negotiate Better NNN Terms
The base rent in an NNN lease gets most of the negotiating attention. But the NNN provisions themselves often have more impact on your total occupancy cost over the lease term. Here are the key points to negotiate:
- Get a CAM cap of 3–5% annually, non-cumulative if possible.
- Define CAM narrowly. Request a specific list of included expenses rather than a broad "all costs of operating and maintaining the property" definition.
- Exclude capital expenditures or require amortization over useful life (not lease term).
- Cap management fees at a reasonable percentage (3–4% is fair; 8% is excessive).
- Negotiate audit rights with a cost-reimbursement provision for material overcharges.
- Request a base year or fixed stop to limit your exposure to increases only.
- Ensure proportionate share is calculated correctly. Verify the total leasable square footage used in the denominator, and ensure vacant spaces are not excluded from the calculation (which would inflate your share).
For a broader understanding of why leases are structured to favor landlords and how to push back, read our guide on the power imbalance in commercial leasing.