Triple net charges usually run $3 to $9 per square foot per year on top of base rent, with property type, location, and building age driving where you land in that range. For a 2,000-square-foot retail space, that works out to roughly $6,000 to $18,000 a year beyond the advertised rental rate. Multi-tenant retail in busy urban corridors can push past $12 per square foot. Suburban strip centers and industrial warehouses often sit near the bottom. The gap between the number on the listing and your actual monthly check is what trips up most first-time commercial tenants, so it pays to understand what each piece of the NNN bill is doing before you sign.
What the Three Charges Cover
The “triple” in triple net refers to three separate costs the tenant takes on beyond base rent: property taxes, building insurance, and common area maintenance. In a gross lease, the landlord absorbs these and bundles everything into one rent number. In an NNN lease, they pass through to you.
Property Taxes
Your share is based on the property’s assessed value multiplied by the local tax rate, which can stack county, city, school district, and special assessment layers on top of each other. A property assessed at $200,000 in a jurisdiction with a 2% combined rate produces a $4,000 annual bill. Reassessments happen periodically, and when values climb, so does your NNN cost, sometimes significantly between lease years.
Building Insurance
The second net covers the premium on the policy protecting the physical structure from fire, storms, liability claims, and other covered events. The landlord selects the policy and coverage levels; you reimburse the cost. Properties in coastal or disaster-prone areas carry noticeably higher premiums, and commercial rates have been climbing in recent years. Ask to see the declarations page so you know what you’re paying for.
Common Area Maintenance (CAM)
CAM covers upkeep of shared spaces: landscaping, parking lot repairs, exterior lighting, lobby cleaning, snow removal, security, and similar services. It’s the most variable of the three. Taxes are set by the assessor, and insurance is locked in for the policy period, but maintenance costs swing year to year depending on weather damage, deferred repairs, or how aggressively the landlord decides to spend. In a multi-tenant shopping center, the CAM portion can add up fast, and it deserves the closest scrutiny when you review the lease.
What Pushes the Number Up or Down
Property type matters more than most tenants expect. Industrial warehouses tend to carry the lowest NNN costs because they have minimal common areas, few landscaping demands, and simple building envelopes. Retail centers sit at the other extreme, with extensive parking lots, constant aesthetic upkeep, and higher security needs. Office buildings fall in between, with elevator maintenance, lobby staffing, and HVAC systems driving CAM.
Geography plays an equally large role. Coastal properties face insurance premiums that can be multiples of what inland buildings pay. In jurisdictions with high commercial property tax rates, the tax portion alone can eat up $4 to $6 per square foot. Two otherwise identical buildings in different counties can carry NNN rates that differ by 50% or more on location alone.
Building age shows up in a less obvious way. Newer buildings often come with absolute NNN terms (more on that below) that shift more cost to the tenant but tend to produce fewer surprises. Older buildings carry standard NNN terms and more repair risk inside the base number.
How Your Share Is Calculated in a Multi-Tenant Building
If you’re leasing space in a building with other tenants, you don’t pay the full tax bill or the entire insurance premium. You pay a pro-rata share based on the percentage of the building your space occupies. Divide your leased square footage by the total rentable square footage, and that percentage is your share of every NNN expense.
Lease 3,000 square feet in a 30,000-square-foot retail center and your pro-rata share is 10%. If building property taxes run $60,000, you owe $6,000. If insurance costs the building $18,000, your share is $1,800. The same percentage applies to CAM. Verify that the total rentable square footage figure the landlord uses actually matches the building. An inflated denominator (or a deflated one that excludes vacant space) changes your share in ways that aren’t obvious at a glance.
Putting It Together: Your Total Occupancy Cost
The math is simple. Add the base rent per square foot to the NNN rate per square foot, multiply by your total square footage, and divide by twelve for the monthly payment. If base rent is $20 per square foot and NNN charges are $5 per square foot, you’re at $25 per square foot total. For a 3,000-square-foot space, that’s $75,000 annually, or $6,250 per month.
Keep this comparison in mind when you’re weighing two spaces with different base rents. A $18-per-foot space with $9 NNN costs more than a $22-per-foot space with $4 NNN, even though the first listing looks cheaper.
Why the Monthly Number Isn’t Final
The NNN portion is almost always an estimate. The landlord projects what taxes, insurance, and CAM will cost for the coming year, divides your pro-rata share into twelve monthly installments, and collects it alongside your base rent. After the fiscal year closes, a reconciliation statement compares what you paid in monthly estimates against what the building actually spent. If actual costs ran higher, you owe the difference. If they ran lower, you get a credit.
These statements deserve real scrutiny. Common errors include capital improvements classified as routine maintenance, costs the lease excludes being billed anyway, math errors in pro-rata share calculations, and expenses from one fiscal year bleeding into another. Most commercial leases give tenants the right to audit the landlord’s books supporting the reconciliation, typically within 30 to 180 days of receiving the statement. One rule to remember: do not withhold rent while disputing a reconciliation charge. In virtually every commercial lease, withholding rent triggers a default, even if your dispute is valid. Pay under written protest to preserve your rights.
Costs That Should Not Appear in Your NNN Bill
Not every expense a landlord incurs belongs in your NNN charges. Well-drafted leases include exclusion lists that carve out costs the tenant shouldn’t bear. Costs that typically shouldn’t pass through to tenants include:
- Debt service, mortgage interest, or ground lease rent — these are ownership costs.
- Broker commissions, advertising for new tenants, and legal fees for negotiating other tenants’ leases.
- Attorney fees, court costs, or judgments from the landlord’s disputes with other tenants.
- Capital improvements that increase the building’s value, as opposed to routine maintenance, though some leases try to amortize these into CAM.
Many landlords also use third-party property management companies, and those fees often get passed through as part of NNN charges. Base management fees for commercial properties typically run 3% to 6% of gross rents collected. A broadly worded operating-expense clause lets the landlord pass through technology platform costs, employee expenses, and administrative overhead on top of that. A well-negotiated lease caps management fees at a specific percentage or dollar amount per square foot.
Standard NNN vs. Absolute NNN
The phrase “triple net” alone doesn’t tell you who pays when something major breaks. In a standard NNN lease, the landlord typically keeps responsibility for structural components: roof, exterior walls, foundation, and major plumbing or electrical systems. The tenant handles day-to-day operating costs and routine maintenance.
An absolute NNN lease shifts everything to the tenant, including the big-ticket structural items. These are most common with credit tenants in single-tenant buildings, where the landlord is essentially a passive investor collecting rent. Newer buildings are more likely to come with absolute terms because structural failure risk is low. Older buildings tend to stay standard because tenants are reluctant to accept replacement risk on aging infrastructure. Read the maintenance and repair section word by word before you sign. A $40,000 roof replacement is a very different story depending on which version you’re in.
Ways to Keep the Number Down
Tenants have more room to negotiate NNN terms than many realize, particularly in soft markets or when the landlord has vacancy to fill.
CAM Caps
A CAM cap limits how much your share of controllable common area expenses can rise each year, typically 3% to 6% over the prior year. “Controllable” is doing the heavy lifting. Landlords will insist that property taxes, insurance, utilities, and security sit outside the cap because they can’t control what the assessor or the insurance company charges. That’s a reasonable position, but it means the cap only protects you against discretionary spending. Push for the cap percentage to be as low as possible and the definition of controllable expenses to be as broad as your leverage allows.
Base Year Provisions
Under this structure, the landlord absorbs NNN costs at whatever level they were during a designated base year, and you pay only increases above that level. If the base year total operating cost for the building is $980,000 and costs rise to $1,185,000 three years later, a tenant with a 12% pro-rata share owes $24,600 for the overage rather than their full share of all expenses. Negotiate for a base year that reflects normal operating conditions, not an unusually low year that will make every subsequent year look like an increase.
Exclusion Lists and Audit Rights
Get explicit exclusion language written into the lease for debt service, leasing commissions, legal fees related to other tenants, and capital improvements. Vague language invites disputes. Separately, negotiate audit rights that give you at least 120 days from receiving the reconciliation statement to review the landlord’s books. Some leases require the landlord to reimburse your audit costs if the audit reveals overcharges above a certain threshold, which is worth asking for even when it’s a hard sell.