Under a triple net lease, triple net lease expenses are the three categories of property costs you pay on top of base rent: real estate taxes, building insurance, and common area maintenance. Together these are the “nets,” and in retail, office, and industrial space they can add up to something close to the base rent itself. What you actually owe each month depends on your share of the building, how the lease defines each category, and how tightly the document limits the landlord’s discretion.
The Three Nets and How Your Share Is Calculated
Each net is billed as a pro-rata share. If you occupy 3,000 square feet of a 30,000-square-foot building, you typically owe 10% of the bill in each category.
Real estate taxes. Local governments assess the property based on its value, and your share tracks your square footage. Most landlords collect an estimated monthly amount alongside rent, pay the taxing authority directly, and reconcile at year-end. Because you are paying the tax, the assessment matters to you, but the right to appeal traditionally belongs to the owner. Some courts have recognized that a tenant contractually obligated to pay the taxes under a net lease may also have standing to file an appeal, but this varies by jurisdiction. If it matters, negotiate a lease clause that either lets you initiate the appeal or requires the landlord to do so at your request.
Building insurance. The second net is your share of the premiums for the property’s coverage. That usually means insurance on the structure against fire and storms, plus general liability for common areas like hallways, lobbies, and parking lots. This coverage protects the landlord’s building, not your business. You will still need your own commercial general liability, property coverage for inventory and equipment, and often rent interruption insurance so payments to the landlord continue if a casualty closes the space.
Common area maintenance (CAM). The third net covers operating and maintaining shared spaces. In a shopping center that is the parking lot, sidewalks, landscaping, exterior lighting, and shared restrooms; in an office building it is the lobby, elevators, stairwells, and corridors. Typical line items include snow removal, landscaping, parking lot resurfacing, security, janitorial services, and utilities for shared areas. Many landlords also add a management fee on top of total operating expenses. CAM is the most contentious of the three because the category is broad and the landlord decides what goes in it.
What Landlords Try to Slip Into CAM
Not everything a landlord spends belongs in CAM. If the lease simply says you pay “all operating expenses,” you have very little leverage to dispute a charge later. Push for specific written exclusions:
- Capital improvements such as a new roof or a lobby renovation, which add long-term value to the landlord’s asset rather than covering routine operations.
- Mortgage payments and other debt service on the property.
- Leasing commissions and advertising to find new tenants.
- Legal fees tied to the landlord’s disputes or negotiations with other tenants.
- Costs already reimbursed by insurance or warranties.
- General corporate overhead of the landlord’s management company that is not tied to this specific building.
Caps on Annual Increases
Even with exclusions, CAM can climb unpredictably. A common protection is a cap on annual increases in controllable operating expenses. Caps in the 3% to 5% range are common starting points. Controllable expenses typically include management fees, routine maintenance, and utilities. Property taxes and insurance premiums are usually excluded from the cap because the landlord cannot influence what the government assesses or what insurers charge.
Capital Expenditures vs. Routine Maintenance
This is where most disputes happen. Replacing a parking lot light bulb is clearly maintenance. Installing an entirely new parking surface is clearly a capital improvement. The gray area between the two is large, and the lease language decides who pays.
Under a standard triple net lease, routine maintenance is the tenant’s problem while major structural work and capital replacements stay with the landlord. You handle HVAC filter changes, parking lot patching, and minor plumbing repairs. The landlord absorbs the cost when the entire HVAC system or roof needs replacement. The trouble is that “routine” versus “capital” is a judgment call. A landlord’s accountant might classify a $15,000 parking lot resurfacing as maintenance while you reasonably see it as a capital improvement.
The cleanest protection is a lease that sets a dollar threshold: anything above the number is treated as a capital expenditure. Some leases allow the landlord to amortize large capital costs over their useful life and pass through only the annual amortized amount as an operating expense. That is a middle ground. If you accept it, make sure the amortization period is reasonable and that your obligation to pay stops when your lease term ends.
Year-End Reconciliation and the True-Up Bill
Triple net charges are rarely billed at their exact amounts month to month. The landlord estimates your annual share of taxes, insurance, and CAM, divides that estimate by twelve, and collects it monthly with rent. At the end of the calendar or lease year, the landlord reconciles the estimates against actual expenses and sends a reconciliation statement.
If the estimates ran high, you get a credit against future payments. If they ran low, you owe the difference. These true-up bills can be surprisingly large in years when tax assessments jump, insurance premiums spike after a regional disaster, or the landlord undertakes significant maintenance. Budgeting a cushion above your monthly estimates helps absorb the hit. The reconciliation statement should also carry enough detail for you to verify every line, which is where audit rights come in.
Auditing the Landlord’s Charges
Landlord billing errors on operating expenses are not rare, and they almost always run in the landlord’s favor. An audit clause gives you the right to review the landlord’s books, receipts, and invoices supporting your bill. Without one, you are trusting the math.
A well-drafted audit clause gives you at least 60 to 90 days after receiving the reconciliation to request a review. It lets you hire an auditor of your choosing. Some landlords try to restrict audits to large accounting firms or prohibit contingency-fee auditors; both restrictions exist to make the right hard to use, and both are worth pushing back on.
If the audit turns up an overcharge, the landlord should reimburse you. Many leases also provide that the landlord pays the cost of the audit itself when the overcharge exceeds a set percentage, commonly around 3% to 5% of the total billed amount. Under a sample lease filed with the SEC, the tenant bore the cost of any review at its own expense but was entitled to prompt reimbursement of any overpayment the review uncovered.1SEC.gov. Commercial Triple Net Lease (Exhibit 10.13)
Costs That Ride Along With the Three Nets
The three nets are the headline expenses, but a triple net lease usually carries several other obligations.
Utilities and Interior Upkeep
You pay for all utilities consumed within your space: electricity, gas, water, internet, and trash removal. You are also responsible for interior maintenance and non-structural repairs. That includes plumbing within your walls, an HVAC unit dedicated to your space, flooring, and repainting. Structural elements such as the foundation, load-bearing walls, and roof stay with the landlord under a standard NNN lease. An absolute net or “bondable” lease can shift even those to you, including the obligation to rebuild after a casualty regardless of whether insurance proceeds are sufficient. Absolute net leases are rare outside single-tenant properties leased to credit-worthy national brands.
Your Own Insurance
Separately from your share of the building’s premiums, you need your own commercial general liability policy, property coverage for your belongings and improvements, and potentially workers’ compensation. The lease will set minimum coverage limits and usually require you to name the landlord as an additional insured.
Personal Guarantees
If your business is new or lacks a strong credit history, expect the landlord to require a personal guarantee. You become personally liable for the lease obligations, which can expose personal savings, investment accounts, and in some cases your home if the business defaults. A “good guy guarantee” is a more limited version where personal exposure ends once you vacate and give proper notice, but the specific conditions vary widely.
Deducting NNN Payments on Your Taxes
If you use the leased property for your trade or business, the rent and operating expenses you pay under a triple net lease are generally deductible as ordinary business expenses. Federal law allows a deduction for “rentals or other payments required to be made as a condition to the continued use or possession” of business property in which you have no ownership equity.2Office of the Law Revision Counsel. 26 U.S. Code 162 – Trade or Business Expenses That language is broad enough to cover base rent, your share of taxes, insurance premiums, and CAM.
The IRS treats rent as deductible in the year it applies to. If you prepay rent covering more than 12 months, a cash-basis taxpayer can only deduct the portion that applies to the current tax year and must spread the rest over the period it covers.3Internal Revenue Service. Publication 535 – Business Expenses Because your payments are broken into categories rather than bundled into one rent figure, keep records that support each category separately.
What to Negotiate Before You Sign
A triple net lease is not a take-it-or-leave-it document, even when a landlord presents it that way. The clauses worth fighting hardest for are the ones that limit your exposure to unpredictable costs.
- A written list of CAM exclusions rather than a vague “all costs reasonably incurred.”
- An annual cap of 3% to 5% on controllable operating expenses.
- A dollar threshold above which an expense counts as a capital improvement and becomes the landlord’s responsibility, or at minimum is amortized over a reasonable useful life.
- Audit rights of at least 90 days, your choice of auditor, and landlord-paid audit costs when overcharges exceed a set percentage.
- A base year stop, more common in office leases, where the landlord covers operating expenses up to the first-year amount and you pay only the increases above that baseline in later years.
- A tax appeal clause giving you the right to challenge the assessment or requiring the landlord to do so at your request and expense.