A triple net lease, often written as NNN, is a commercial real estate agreement in which the tenant pays base rent and also covers the three big ownership costs of the building: property taxes, insurance, and maintenance. Most of these leases run 10 to 15 years, and some go longer, which makes them one of the longest financial commitments in commercial real estate.1Legal Information Institute. Triple Net Lease The landlord receives rent that functions as near-pure income. The tenant, in exchange, gets near-total control of the property and takes on nearly every expense of running it.
What the Three Nets Actually Cover
The “triple” in triple net refers to three expense categories that sit on top of base rent. Each one moves a different piece of ownership cost onto the tenant.
Property Taxes
The tenant pays every real estate tax assessed against the land and building for the full term. Rate changes, reassessments, and special levies all pass through. The tenant pays whatever the bill says, when it’s due. Most leases also require the tenant to send paid tax receipts to the landlord as proof. Falling behind can trigger a tax lien, which is almost always treated as a lease default.1Legal Information Institute. Triple Net Lease
Insurance
The tenant carries property and liability insurance on the building at the coverage levels the lease specifies. Property coverage protects the structure against fire, storms, and similar hazards. General liability coverage protects against injuries on the premises. The lease almost always requires the tenant to name the landlord as an additional insured and to deliver proof of coverage every year. If the policy lapses, the landlord typically has the right to buy replacement coverage and bill the tenant for it at a premium.
Common Area Maintenance (CAM)
CAM covers everything needed to keep the exterior and shared areas functional: parking lot repairs, landscaping, snow removal, exterior lighting, security. In a standalone building leased to one tenant, CAM is usually straightforward because the tenant controls the entire site. In a multi-tenant property, CAM gets allocated based on each tenant’s share of total leasable square footage. This is the category where disputes most often arise, because what qualifies as a legitimate CAM charge is only as clear as the lease language defines it.
How a Triple Net Lease Compares to Other Net Leases
NNN is the far end of a spectrum. Knowing where it sits relative to the alternatives clarifies exactly what a tenant is agreeing to.
- Gross lease: the tenant pays a flat rent and the landlord covers all operating expenses. Common in multi-tenant office buildings where the landlord wants centralized control.
- Modified gross lease: the tenant pays base rent plus some operating expenses. The split is negotiated. There is no standard formula.
- Single net lease (N): the tenant pays base rent plus property taxes. The landlord handles insurance and maintenance.
- Double net lease (NN): the tenant pays base rent plus property taxes and insurance. The landlord retains maintenance and structural repairs.
- Triple net lease (NNN): the tenant pays base rent plus taxes, insurance, and maintenance. The landlord’s rent is essentially pure income.
There is also an absolute net lease, sometimes called a bondable lease, and the distinction matters more than most tenants realize. In a standard NNN lease, the landlord typically still bears responsibility for major structural components: the roof, the foundation, the exterior walls. In an absolute net lease, the tenant takes on everything, including structural repairs and even full rebuilds after a casualty. Absolute net leases are common with credit tenants like national pharmacy chains or fast-food franchises that want complete autonomy over the building. If a lease is presented as “NNN,” the first thing to check is whether it is actually absolute net in disguise.
Base Rent and Escalations
Financial obligations in an NNN lease split into two buckets. Base rent is the fixed monthly amount paid for the right to occupy the space, usually calculated per square foot. Additional rent is everything else: the pass-through costs for taxes, insurance, and CAM. Because additional rent only reimburses actual operating costs, the landlord’s base rent arrives as net income.
Almost every NNN lease includes a mechanism to raise base rent over time. The two most common approaches are fixed-percentage escalations and Consumer Price Index adjustments. A fixed escalation might increase rent by 2% every year or 10% every five years. The numbers are locked in at signing. CPI escalations tie increases to inflation, recalculating each year based on the percentage change in the index between two specified periods. The Bureau of Labor Statistics recommends using the CPI-U (All Urban Consumers) index with U.S. City Average data rather than regional indexes, which have smaller sample sizes and more volatility.2U.S. Bureau of Labor Statistics. How to Use the Consumer Price Index for Escalation
A well-drafted CPI clause includes both a cap and a floor. The cap limits how much rent can rise in any single adjustment period, which protects the tenant from runaway inflation. The floor guarantees a minimum increase regardless of what the index does, protecting the landlord if inflation drops to near zero. Signing a CPI-linked lease without a cap means taking on open-ended rent risk that can compound dramatically over 15 years.
Day-to-Day Maintenance Obligations
Beyond writing checks for the three nets, an NNN tenant functions as the building’s facilities manager. The scope runs from HVAC systems to plumbing to parking lot surfaces.
Heating and cooling is the biggest ongoing commitment. Most leases require the tenant to maintain a service contract with a licensed HVAC technician on a quarterly or semi-annual inspection schedule. Skipping preventive maintenance is the fastest way to convert a routine expense into a five-figure emergency. When a compressor fails in July because filters have not been changed in two years, the tenant pays for the replacement and the landlord has no obligation to help.
Plumbing and electrical follow the same logic. A slow drain is the tenant’s problem. A tripped breaker is the tenant’s problem. The lease typically requires the tenant to keep all building systems in good working order throughout the term, which means addressing small issues before they become structural ones. The tenant hires and manages every third-party contractor, from roofers to plumbers to electricians, without landlord involvement. That autonomy is one of the trade-offs: the tenant can prioritize repairs that matter to the business, but there is no landlord to call when something breaks.
Caps on Major Repairs
Some NNN leases include dollar caps on specific maintenance categories, especially HVAC. A negotiated lease might cap tenant responsibility at $15,000 per occurrence or $50,000 per year for HVAC repairs, with the landlord reimbursing anything above those thresholds. These caps are not standard. They are negotiated, and they often come with conditions, such as the tenant first completing agreed-upon system upgrades and maintaining a current certification from the HVAC contractor that the systems are in proper working order. A tenant who does not negotiate caps on major mechanical systems is accepting unlimited exposure to replacement costs that can easily reach six figures.
Capital Improvements and Structural Work
The line between maintenance and capital improvement is where NNN disputes most often land. Patching a roof leak is maintenance. Replacing the entire roof is a capital improvement. That distinction determines who pays and how the cost gets allocated.
In a standard NNN lease, the landlord keeps responsibility for structural components: roof, foundation, exterior load-bearing walls, and the building’s structural frame. The tenant handles everything else. In an absolute NNN lease, the tenant picks up structural costs too, which is why the lease language has to be read carefully before signing.
When capital improvements are allowed as pass-through charges, sound accounting practice calls for amortizing the cost over the useful life of the improvement rather than billing the tenant for the entire amount in a single year. A new roof with a 20-year useful life should be spread across 20 years of operating expense charges. That prevents the inequitable result of one tenant bearing the full cost of an improvement that will benefit future tenants long after the current lease ends. For improvements designed to reduce operating costs, such as an energy management system, the annual amortization charge should not exceed the actual savings the improvement generates.
Catastrophic Risks the Lease Has to Address
Casualty and Rebuilding
When a building suffers major damage, the lease should specify who rebuilds and what happens to rent in the meantime. In most NNN structures, the tenant carries the casualty insurance and is responsible for restoration using the insurance proceeds. The tenant typically also restores their own interior improvements, fixtures, and equipment.
Rent abatement during repairs is not automatic. Well-negotiated leases provide that rent is abated in proportion to how much of the premises cannot be occupied, but only if the tenant did not cause the damage through gross negligence or intentional conduct. If the tenant caused the casualty, most leases require full rent to continue while the tenant funds repairs out of pocket.
For a total loss, the lease should give the tenant the right to terminate rather than force a rebuild that no longer makes business sense. Whether a loss qualifies as “total” is usually tied to whether the building can be restored within a specified timeframe or whether the tenant can still use the premises for its intended business purpose. A lease that does not clearly define total loss is a lease that will end up in litigation.
Eminent Domain
When the government condemns part or all of a leased property, the tenant’s rights depend on whether the lease contains a condemnation clause. Without one, the tenant is entitled as a matter of law to share in the condemnation award based on the value of the remaining leasehold interest, essentially what the right to occupy the space at below-market rent was worth.
Landlord-favorable leases often require the tenant to waive all claims to the condemnation award in exchange for lease termination. Tenant-favorable versions preserve the right to pursue a separate claim for moving expenses, unamortized improvements, and business interruption losses. In a partial taking, the lease may continue for the remaining usable portion, and the tenant should insist on a rent reduction proportional to the space lost.
Environmental Contamination
Environmental liability is the sleeper risk in any NNN lease. Under federal law, liability for hazardous substance contamination flows from a party’s status as an “owner or operator” of a facility, and a tenant operating a business on the property can qualify as an operator.3Office of the Law Revision Counsel. 42 USC 9607 – Liability A tenant can face federal cleanup liability regardless of what the lease says about who is responsible.
Lease language typically splits contamination into two categories. For conditions that existed before the tenant took possession, the allocation depends on negotiating leverage. Landlord-favorable leases require the tenant to remediate pre-existing contamination at its own expense. Tenant-favorable leases include indemnification from the landlord for anything that predates the lease. For contamination the tenant causes during the term, the tenant is almost universally responsible for cleanup, and that obligation survives lease termination, meaning the tenant can face remediation costs years after vacating.
Both parties benefit from an environmental audit before the lease begins. Without a baseline assessment, the landlord will struggle to prove the tenant caused the contamination and the tenant will struggle to prove they did not. Skipping the Phase I environmental assessment to save a few thousand dollars is one of the most expensive shortcuts in commercial leasing.
ADA Compliance
The Americans with Disabilities Act requires removal of architectural barriers in existing public accommodations where removal is readily achievable. Federal law places this obligation on anyone who “owns, leases (or leases to), or operates” a place of public accommodation.4Office of the Law Revision Counsel. 42 USC 12182 – Prohibition of Discrimination by Public Accommodations The landlord and tenant can agree in the lease about who will actually perform and pay for modifications, but both remain legally liable if compliance falls short. An NNN lease that assigns all ADA costs to the tenant does not eliminate the landlord’s exposure; it just determines who pays between the two of them, not who gets sued by a third party.
Annual Reconciliation and Audit Rights
Landlords do not wait until year-end to collect additional rent. At the start of each fiscal year, the landlord estimates total costs for taxes, insurance, and CAM, then bills the tenant in equal monthly installments alongside base rent. At year-end, a reconciliation compares estimated payments against actual spend. Overpayments get credited toward future rent. Underpayments require a catch-up from the tenant.
This is where things get adversarial more often than landlords like to admit. Reconciliation statements can include charges that do not belong, math errors, or costs the lease never intended to pass through. An entire cottage industry of lease audit firms exists because landlord accounting errors in CAM reconciliation are common.
The right to audit the landlord’s books is one of the most important provisions a tenant can negotiate. Standard audit clauses require the tenant to request an audit in writing within a set window, often 30 days, after receiving the reconciliation statement. The audit typically happens at the landlord’s office during business hours with advance notice. The tenant has to share audit results with the landlord within a specified period. If the audit shows an overcharge, the landlord credits the excess toward future rent or issues a reimbursement.
Most leases restrict audit rights to tenants who are current on their obligations, meaning a default can forfeit the right. Some leases limit how far back an audit can reach, often the current year plus one prior year. Tenants who let reconciliation statements pile up may lose the ability to challenge older charges entirely. Treat every reconciliation statement as a deadline.
What to Negotiate Before Signing
NNN lease forms are usually drafted by landlords, and the default language favors the landlord on almost every contested point. Negotiating before signing can materially reduce financial exposure across a 10- to 15-year term.
- CAM exclusions. Define specifically what costs cannot be passed through as CAM. Capital expenditures that benefit the building beyond the lease term, costs attributable to other tenants in a multi-tenant building, and the landlord’s own administrative overhead are common exclusions worth fighting for.
- Controllable expense caps. Some operating costs are within the landlord’s control, like property manager wages or security. An annual cap on controllable expenses, often tied to a percentage increase over the prior year, prevents the landlord from inflating these charges.
- Capital expenditure amortization. If the lease allows capital improvement costs to be passed through, insist they be amortized over useful life rather than charged in a lump sum.
- Repair caps. Negotiate dollar caps on major mechanical system repairs, particularly HVAC, with the landlord absorbing costs above the cap.
- Audit rights. Ensure the lease grants the right to audit operating expenses annually, with a meaningful window to exercise the right and a remedy (rent credit) if overcharges are found.
- Renewal options. NNN tenants commonly negotiate a series of five-year renewal options. Check whether the renewal rent resets to fair market value or continues with the existing escalation schedule. The difference across a five-year extension can be substantial.
- Property tax appeals. Because the tenant pays taxes directly, many leases let the tenant challenge an inflated assessment, usually at the tenant’s own cost. Some require landlord consent before filing, so confirm the language before hiring an appraiser.
A triple net lease is not inherently a bad deal for a tenant. It can be the right structure for a business that wants control of its building and predictable total occupancy costs. But the label hides a long list of obligations that only become visible when something goes wrong, and the time to find them is before signing, not after the first reconciliation statement arrives.