A triple net lease is a commercial lease in which you pay a base rent plus the property’s three main operating costs: real estate taxes, building insurance, and common area maintenance. It is the dominant structure for single-tenant retail and industrial space in the United States, and it shifts most of the property’s financial risk from the landlord to you. In exchange, the quoted base rent is lower than what a landlord would charge under a lease that bundles those costs. Your actual monthly bill, though, moves with expenses you don’t fully control.
The Three Nets
The name comes from the three expense categories the tenant absorbs on top of base rent. Each behaves differently.
Property Taxes
You typically pay the entire annual property tax assessment, either directly to the taxing authority or as a reimbursement to the landlord. Taxes are not fixed. Local governments reassess property values on their own schedule, and a reassessment in a growing area can push the bill up sharply from one year to the next. You have no control over the assessment itself, but in many jurisdictions the lease can give you standing to appeal on the landlord’s behalf. That right is worth negotiating in if it isn’t already there.
Building Insurance
The second net is a hazard or casualty policy on the building itself, protecting against fire, storms, and similar events. You pay the premiums, and the landlord usually dictates the coverage amounts, the insurer, and the terms, since it is their asset being insured.
This policy covers only the structure and permanent improvements. It does not cover your inventory, your fixtures, or lost revenue if the property becomes unusable. You need a separate commercial policy for those exposures, and tenants routinely underestimate what that additional coverage costs when they budget total occupancy.
Common Area Maintenance
Common Area Maintenance, or CAM, is the third net and the messiest one. CAM covers ongoing costs to keep the property operational: landscaping, parking lot repairs, exterior lighting, snow removal, utility systems, and the like. In a multi-tenant property, these charges are split proportionally by square footage. In a single-tenant building, you absorb all of them.
The lease defines what counts as a CAM expense, and the line between routine maintenance and a capital expenditure is where landlords and tenants clash most often. Resurfacing a parking lot generally reads as maintenance. Replacing the entire lot starts to look like a capital improvement, and whether it lands on your bill depends entirely on how the lease is written. The same fight plays out over roofs, HVAC systems, and structural elements.
Most NNN leases use an estimated monthly CAM payment based on the prior year’s actual costs. At year-end, the landlord reconciles those estimates against what was actually spent. If they underestimated, you get a bill for the difference. If they overestimated, you get a credit. This reconciliation can produce unpleasant surprises, which is why experienced tenants negotiate caps and keep a cash reserve for the true-up.
What You Actually Pay
The base rent in an NNN lease does not reflect what you will spend. Your real cost is base rent plus all three nets, and the gap can be substantial. A simplified example for a 2,000-square-foot retail space:
- Base rent: $25 per square foot per year, or $50,000 annually
- Property taxes: $6 per square foot, or $12,000
- Building insurance: $2 per square foot, or $4,000
- CAM charges: $5 per square foot, or $10,000
- Total occupancy cost: $38 per square foot, or about $76,000 annually ($6,333 per month)
The pass-throughs add more than 50% to the base rent in this example. That gap is why comparing NNN rents to gross lease rents on base rent alone is a common and expensive mistake. A gross lease quoting $36 per square foot may cost less than an NNN lease quoting $25 once the nets are added. Compare total occupancy cost, not the headline number.
Standard NNN vs. Absolute NNN
Not every triple net lease transfers the same amount of risk, and the difference matters.
Under a standard NNN lease, you cover taxes, insurance, and maintenance, but the landlord usually keeps some responsibility for major structural components like the roof and foundation. If the building needs a new roof, that cost often stays with the landlord or gets split through an amortization formula where you pay a proportional share each year based on the improvement’s useful life.
An absolute NNN lease, sometimes called a bondable lease, goes further. The tenant takes on every property expense without exception, including structural repairs and full replacement of building systems. These leases are typically non-cancelable and remain in force even if the building is destroyed; the tenant is still responsible for rebuilding or continuing to pay rent. National pharmacy chains, fast-food franchises, and other creditworthy tenants with long-term locations commonly sign absolute NNN leases.
For investors, absolute NNN is attractive because the income stream is nearly passive. For tenants, the lower base rent comes with the risk of absorbing a six-figure roof replacement or structural repair that would have been the landlord’s problem under a standard NNN. Know which version you are signing.
How NNN Fits Against Other Commercial Leases
NNN sits at one end of a range that runs from full tenant responsibility to full landlord responsibility.
Gross Lease
A gross lease, also called a full-service lease, is the opposite of NNN. You pay one flat rate that covers base rent, taxes, insurance, and maintenance. The landlord absorbs cost fluctuations, and your monthly bill is predictable. In exchange, the quoted rent is higher, since the landlord builds in a cushion. Gross leases are most common in multi-tenant office buildings.
Modified Gross Lease
A modified gross lease splits responsibilities. You pay base rent plus some operating costs; the landlord covers the rest. The exact split varies. Some modified gross leases use a base-year approach, where the landlord covers operating expenses at the level incurred in the first lease year and you pay only the increases in later years.
Double Net Lease
A double net (NN) lease sits between modified gross and NNN. You pay base rent plus taxes and insurance, but the landlord keeps full responsibility for maintenance and structural repairs. It shows up in multi-tenant properties where the landlord wants to control maintenance quality directly.
Terms to Negotiate Before You Sign
The lease document controls everything in an NNN arrangement, and the default terms almost always favor the landlord. Most of the pain tenants feel later comes from failing to negotiate a handful of specific provisions.
CAM Caps and Controllable Expenses
The single most important protection is a cap on controllable CAM expenses. Controllable expenses are the costs the landlord can influence: landscaping contracts, janitorial, vendor selection. Uncontrollable expenses like property taxes and insurance premiums are usually excluded from the cap because neither party sets those rates.
A standard cap limits annual increases in controllable expenses to somewhere in the 3% to 5% range. Watch whether the cap is cumulative or non-cumulative. A cumulative cap lets the landlord roll unused increase capacity from a low-cost year into a future year, eroding the protection over a long term. A non-cumulative cap prevents that rollover. Over a ten-year lease, the difference can run into tens of thousands of dollars.
Expense Exclusions
Not every property cost belongs on your bill. Experienced tenants negotiate explicit exclusions:
- Capital improvements, either excluded entirely or amortized over useful life so you pay a small annual share rather than a full lump sum
- Leasing costs like broker commissions, legal fees for other tenants’ leases, and vacant space build-outs
- Landlord financing costs such as mortgage interest, loan points, and ground lease payments
- Remediation of the landlord’s own code violations
- Any cost the landlord recovers through an insurance claim
- Management fees above a set percentage of gross rent, so the fee doesn’t become a hidden profit center
If the lease does not explicitly exclude a cost category, assume it will eventually be passed through. Silence in a lease benefits the drafting party, and the landlord drafted it.
Rent Escalation
NNN base rent rarely stays flat. Escalation clauses come in three common forms: fixed annual increases of roughly 2% to 3%; CPI-tied increases that adjust with inflation; or step-ups that hold rent flat for a defined period, then jump to a new level. The clause applies only to base rent. Your pass-throughs escalate on their own based on actual costs, so the total cost trajectory is steeper than the base rent line alone suggests. Model both together when you project long-term occupancy.
Audit Rights
Your lease should let you audit the landlord’s books on the pass-through expenses. Without an audit clause, you are trusting the landlord’s accounting entirely, and CAM overcharges are common enough that sophisticated tenants treat auditing as routine.
A well-drafted clause gives you a window, typically 90 to 180 days after the annual reconciliation, to request the audit. Some leases require a licensed CPA to perform it. If the audit finds a material overcharge, often defined as more than 3% to 5% of total charges, the landlord usually reimburses your audit costs on top of the refund. Miss the window, and you waive the right for that year. Put the deadline on the calendar the day the reconciliation statement arrives.
What Happens If You Don’t Pay a Pass-Through
Missing a pass-through payment carries the same consequences as missing base rent. Most commercial leases define “rent” to include base rent plus all additional charges, so an unpaid CAM bill or tax reimbursement triggers the same default provisions. The landlord can issue a notice of monetary default and, if you do not cure it within the specified period, pursue eviction, lockout, lease termination, or a lawsuit. Cure periods commonly run 3 to 10 days, and some leases eliminate the cure period for repeated late payments.
This surprises some tenants. They dispute a CAM charge, withhold payment while arguing, and land in default. The safer path is to pay under protest and use your audit rights, rather than hand the landlord grounds to terminate the lease.
Tax and Accounting Notes
Base rent and all three pass-throughs are deductible as ordinary business expenses when you use the property in your trade or business. Federal tax law allows deduction of “rentals or other payments required to be made as a condition to the continued use or possession” of business property, and the property tax and insurance reimbursements you make under the lease qualify on the same basis.1Office of the Law Revision Counsel. 26 USC 162 – Trade or Business Expenses
If your business reports under U.S. GAAP, ASC 842 puts the base rent commitment on your balance sheet as a right-of-use asset and a corresponding lease liability. The pass-through expenses for taxes, insurance, and CAM are variable payments that don’t track an index or rate, so they are generally excluded from the liability and expensed as incurred. A practical expedient can combine lease and non-lease components; talk to your accountant about which treatment fits before you sign.
Finally, build a reserve for the annual CAM reconciliation. If actual expenses exceeded your estimates, the landlord will bill the shortfall, often with a payment window of 30 days or less. A reasonable starting reserve is 5% to 10% of your annual estimated pass-through costs, held in a separate account. Tenants who skip this buffer tend to scramble for cash in the first quarter, exactly when the prior year’s true-up lands.