A triple net lease (NNN) means you pay base rent plus your proportional share of property taxes, building insurance, and operating expenses — costs that a gross lease would bundle into one number. In office and industrial leasing, NNN rents often look deceptively low: a space quoted at $2.84/sf/month NNN can easily run $3.50–$4.00/sf/month once operating expenses are added. Before you sign anything, know exactly what's excluded from that base number.
---
What Is a Triple Net Lease, and How Does It Work?
The term "triple net" refers to three categories of costs that pass through from landlord to tenant:
- Property taxes — the real estate taxes assessed on the building
- Building insurance — the landlord's property and liability coverage
- Operating expenses (OpEx) — maintenance, repairs, utilities for common areas, janitorial, management fees
In a full-service gross lease — the most common structure for traditional office buildings — the landlord bundles all of these into a single quoted rent. You pay one predictable number per square foot per year and the landlord absorbs fluctuations in taxes and maintenance costs.
In a triple net lease, the landlord quotes a lower base rent and bills you separately for your proportionate share of those three buckets. The building's total annual costs are divided among tenants based on their share of total rentable square footage, usually called the "pro-rata share" or "proportionate share."
Why does NNN exist? From a landlord's perspective, NNN leases transfer cost volatility to tenants. If property taxes jump 15% or the HVAC needs a major overhaul, the landlord isn't eating that cost — you are. It also simplifies underwriting for lenders and investors, since the income stream from a NNN property is more predictable. For tenants, the tradeoff is lower face-rent and, theoretically, the ability to audit and contest operating expense charges.
NNN is the dominant structure in retail and industrial real estate in the U.S. It's less universal in office leasing, but it's increasingly common — especially in suburban office parks, flex-industrial buildings, and markets where smaller landlords own boutique office product. If you're looking at office space in NYC, San Francisco, or Boston, you'll run into NNN terms more often than you'd expect, particularly in converted loft buildings, ground-floor office space, or industrial-to-office conversions.
---
What Costs Are and Are Not Included in NNN Rent?
This is where founders get burned. The NNN label doesn't guarantee a standardized list of inclusions and exclusions. Every lease defines the operating expense pool differently. Here's a typical breakdown:
What You're Usually Paying on Top of NNN Base Rent
|
Cost Category |
Who Pays in NNN Lease |
|---|---|
|
Property taxes (pro-rata share) |
Tenant |
|
Building insurance |
Tenant |
|
Common area maintenance (CAM) |
Tenant |
|
HVAC maintenance (common areas) |
Tenant |
|
Property management fees |
Tenant |
|
Janitorial (common areas) |
Tenant |
|
Structural repairs (roof, foundation) |
Landlord (usually) |
|
Capital expenditures |
Negotiable |
|
Utilities (your suite) |
Tenant |
|
Internet / telecom |
Tenant |
How to Read a NNN Quote
If you see a space listed at $2.84/sf/month NNN + $0.54 OpEx, that means:
- $2.84 = base rent (net of all operating expenses)
- $0.54 = estimated operating expense pass-throughs per square foot per month
- Total effective rent = $3.38/sf/month, or roughly $40.56/sf/year
The $0.54 figure is an estimate. Your actual OpEx charges reconcile at year end based on real costs. If actual expenses exceeded the estimate, you owe a "true-up." If they came in lower, you get a credit. Always ask for 2–3 years of historical OpEx reconciliation statements before signing a NNN lease.
---
How Does NNN Compare to Other Commercial Lease Structures?
There are several lease structures between "full gross" and "pure triple net," and the lines blur frequently in practice:
|
Lease Type |
What Tenant Pays |
Predictability |
Common In |
|---|---|---|---|
|
Full Service Gross |
Base rent only (all-in) |
High |
Class A office buildings |
|
Modified Gross |
Base rent + some OpEx (negotiated) |
Medium |
Class B/C & boutique office, sublease |
|
Triple Net (NNN) |
Base rent + taxes + insurance + OpEx |
Low (variable) |
Retail, industrial, flex office |
|
Double Net (NN) |
Base rent + taxes + insurance |
Medium-low |
Less common |
The real question when you're evaluating space: what's my total monthly cost, and how predictable is it? A gross lease at $65/sf/year may look more expensive than a NNN lease at $40/sf/year — but add $18–22/sf in OpEx pass-throughs and the NNN space often costs more. Always compare on a total occupancy cost basis, not headline rent.
For a broader look at how to evaluate lease structures end-to-end, see our breakdown on office lease types.
---
Red Flags to Watch for in a NNN Lease
NNN leases carry real risk if you don't read them carefully. These are the clauses worth flagging for your attorney:
Is There a Cap on Operating Expense Increases?
Without a cap, your OpEx pass-throughs can spike year-over-year with no ceiling. A landlord who defers maintenance for two years and then does a major overhaul can pass the full cost to tenants. Negotiate an OpEx cap — typically 3–5% annual increase on controllable expenses (taxes and insurance are usually excluded since they fluctuate independently).
What's Excluded From the Operating Expense Pool?
A well-negotiated NNN lease excludes from the OpEx pool: capital expenditures (or amortizes them over useful life), leasing commissions for other tenants, the landlord's income taxes, above-market management salaries, and costs reimbursed by insurance or other tenants. If the lease doesn't spell out exclusions, push back.
Are You Paying for the Whole Building's Costs?
Your pro-rata share should be calculated as your rentable square footage divided by the total rentable square footage of the building — not just the occupied portion. Watch for leases that calculate pro-rata share based on occupied space only, which means your share grows as other tenants leave.
Can You Audit the Landlord's Books?
A standard NNN lease gives you the right to audit operating expense statements, typically within 12 months of receiving the annual reconciliation. Make sure this right is in your lease. Most audits surface 5–15% in recoverable overcharges.
---
How NNN Leases Work in NYC, San Francisco, and Boston
The prevalence and structure of NNN leases varies meaningfully by market.
New York City
Traditional Manhattan office leases — especially in Class A towers in Midtown and Class B buildings in Flatiron, NoMad, and Chelsea — are predominantly modified gross or full service gross. You'll see NNN more often in:
- Ground-floor retail with office buildouts
- Industrial-to-office conversions in DUMBO and Williamsburg
- Single-tenant or boutique buildings where the landlord wants to pass through all costs
NYC security deposit norms under a Good Guy Guarantee typically run about 3 months; without one, expect 4–6 months. In a NNN structure, confirm whether the deposit is calculated on base rent only or on estimated total occupancy cost. It matters more than you'd think.
San Francisco
SoMa — the most common landing spot for tech startups — has a mix of gross and NNN product. Older industrial buildings converted to office space frequently use NNN or modified gross structures. Newer Class A buildings in South Beach and near the Embarcadero tend toward full service gross.
The San Francisco Office of the Assessor-Recorder publishes property tax assessment data publicly, which is useful for sanity-checking the property tax component of your NNN pass-throughs before you sign.
Boston
Boston's startup corridor — Kendall Square, the Seaport, and the South End — skews toward gross and modified gross leases in purpose-built office product. NNN terms appear more often in older building stock, flex-industrial spaces in the Innovation District, and suburban markets. Massachusetts governs commercial lease disclosures somewhat differently than NYC or California, so talk to a local real estate attorney before signing any NNN lease in the state.
---
Is a NNN Lease Ever a Good Deal for Startups?
Yes — but it depends on the building, the market, and your negotiating leverage.
NNN leases can work in your favor when:
- Base rent is substantially below market. The OpEx pass-throughs are real costs the landlord would otherwise factor into a gross rent anyway. If the math works out to a lower total occupancy cost, NNN wins.
- The building's operating expenses are low and stable. Newer buildings with efficient systems and lean management produce smaller OpEx bills.
- You can negotiate hard caps and strong audit rights. With those protections in place, your cost exposure is bounded.
- The space is industrial or flex. NNN is standard in that product type, so market comps already reflect it. Fighting the structure wastes negotiating capital you could spend elsewhere.
Where NNN leases create unnecessary risk: early-stage companies with tight cash flow who can't absorb year-end true-up surprises, or founding teams who don't have bandwidth to audit annual reconciliations. If that sounds like you, negotiating toward a modified gross structure — or paying slightly higher gross rent for predictability — is often the smarter call.
Tandem's team works with startup founders across NYC, San Francisco, and Boston to compare NNN and gross options on a true apples-to-apples total cost basis. If you're currently evaluating office space, browse private offices on Tandem to see what's available in your market.
---
Last updated: October 2026
