In commercial real estate, net rent is the portion of a lease payment that buys you only the right to occupy the space. It is quoted per square foot per year and excludes the property’s operating costs: real estate taxes, building insurance, and common area maintenance. Those costs still get paid, but they are billed to you separately on top of the net rent figure. So the number on the listing is the floor of your monthly outlay, not the ceiling, and what you actually spend depends on which of those excluded costs the lease shifts to you and how they are calculated.
How the Net Rent Number Works
Net rent is expressed as a dollar amount per square foot per year. If a landlord lists space at $22.00 per square foot net and you lease 3,000 square feet, the annual net rent is $66,000, or $5,500 a month. That payment covers the physical space and nothing else. It does not include any cost associated with running, protecting, or maintaining the building.
Everything the net rent leaves out falls into three categories that the industry treats as a package: real estate taxes, property insurance, and common area maintenance (usually shortened to CAM). How many of those three you absorb on top of net rent is what defines the type of net lease you’re signing.
The Three Costs Excluded from Net Rent
Real Estate Taxes
Local governments levy property taxes based on the building’s assessed value. In a net lease, the landlord passes that bill to tenants rather than absorbing it. In a multi-tenant building, the total tax bill is divided by the building’s leasable square footage, and each tenant pays a share proportional to the space they occupy. Assessed values can jump after a reassessment or a sale, so this cost can rise without warning. Ask for the most recent tax assessment before signing to set a baseline.
Property Insurance
The landlord carries a master policy on the building’s structure, covering fire, weather, and similar hazards, and the premium is charged back to tenants as a pass-through. That policy protects the building. It does not protect your equipment, inventory, or liability, and most leases require you to carry your own commercial general liability and property coverage on top of the insurance you’re already helping pay for.
Common Area Maintenance
CAM covers whatever keeps the building and its shared spaces running: landscaping, parking lot upkeep, snow removal, elevator servicing, janitorial work in lobbies and hallways, shared utilities, and often a management fee.
The detail worth reading closely is how the lease treats capital expenditures. A new roof or a full HVAC replacement is a capital cost, not a maintenance cost. If the lease doesn’t explicitly exclude capital expenditures from CAM, a landlord could pass an entire roof replacement to tenants in one year. Well-drafted leases either exclude capital items outright or amortize them over their useful life so tenants absorb a small annual slice instead of a lump sum.
CAM caps are worth asking for. A cap limits how much the landlord can raise controllable CAM year over year, commonly in the 3% to 5% range. Controllable items are the ones the landlord can manage, like landscaping and janitorial contracts. Uncontrollable costs such as taxes and insurance premiums usually sit outside the cap.
The Net Lease Spectrum
“Net lease” is really a spectrum, and the number of pass-through categories you take on determines where your deal sits on it.
Gross Lease
Under a gross lease (sometimes called full-service), you pay one flat rate and the landlord covers all three operating cost categories out of it. Your monthly bill is predictable. The tradeoff is price, because landlords build a risk premium into the gross rent to protect themselves against rising taxes, insurance, and maintenance. You’re paying for certainty.
Modified Gross Lease
A modified gross lease splits the three costs between landlord and tenant, but there’s no standard formula. One lease might make you pay insurance while the landlord handles taxes and CAM; another might do the reverse. The label alone tells you almost nothing until you read the actual allocation. This structure is common in office buildings.
Single Net Lease (N)
A single net lease means you pay net rent plus one pass-through, almost always real estate taxes. The landlord keeps insurance and CAM. It’s the lightest net structure and the first point at which your monthly cost becomes partially variable.
Double Net Lease (NN)
A double net lease adds a second pass-through: you pay net rent, taxes, and property insurance. The landlord retains CAM and structural maintenance. Both taxes and insurance premiums can swing year to year, so a double net budget needs room for volatility.
Triple Net Lease (NNN)
The triple net lease is the most common structure in commercial real estate, especially for single-tenant retail and industrial properties. You pay net rent plus all three categories: taxes, insurance, and CAM. Because the tenant carries all the variable operating risk, the net rent on an NNN deal is typically the lowest base rate you’ll see for comparable space.
One point catches tenants off guard. In a standard NNN lease, the landlord usually remains responsible for major structural repairs to the roof, foundation, and exterior walls. Those are capital, not operating, expenses. If a lease under the NNN label tries to shift structural repairs to you, you’re looking at something closer to an absolute net.
Absolute Net Lease
An absolute net lease goes further than triple net by making the tenant responsible for everything, including structural and capital repairs. If the roof needs replacement, that’s your cost. Some absolute net leases, sometimes called bondable or “hell or high water” leases, even require you to keep paying rent and rebuild after a natural disaster. This structure shows up most on long-term single-tenant deals with credit tenants, where the landlord is essentially a passive investor.
Rentable Versus Usable Square Footage
Before you multiply the net rent rate by your square footage, you need to know which square footage the lease uses. Commercial leases almost always quote rent on rentable square feet, not usable square feet, and the gap matters.
Usable square footage is the space inside your suite, measured wall to wall. Rentable square footage adds your proportional share of the building’s common areas: lobbies, hallways, restrooms, elevator banks, mechanical rooms. The ratio between the two is called the load factor, and it typically runs 10% to 15%, sometimes higher.
The math changes fast. A space with 4,000 usable square feet in a building with a 15% load factor is 4,600 rentable square feet. At $25.00 per square foot net, that’s $115,000 a year, not $100,000. The extra $15,000 pays for hallway and lobby space you share with every other tenant. The Building Owners and Managers Association (BOMA) publishes the industry-standard measurement methodology, and most landlords follow it. Ask which standard the landlord used and verify the load factor before signing.
How Your Share of Pass-Throughs Gets Calculated
Knowing which expenses you owe is only half the picture. The mechanism that turns building-wide costs into your specific bill is where the real exposure sits.
Pro Rata Share
Your pro rata share is the percentage of total building expenses you have to pay. Divide the rentable square footage of your space by the total rentable square footage of the building. Lease 5,000 square feet in a 50,000-square-foot building and your pro rata share is 10%. That percentage is then applied to each pass-through category.
Check the denominator. Some landlords use the building’s total square footage, which lowers your percentage. Others use only the leased square footage, which raises it. In a half-empty building, a denominator based only on occupied space can push your pro rata share well above what your footprint alone would suggest.
Base Year
The base year mechanism shows up in gross and modified gross leases. The landlord designates a specific calendar year, usually the first full year of the lease, as the baseline. Total operating expenses in that year become the benchmark. In every year after, you pay your pro rata share only of the amount by which actual expenses exceed the base year total. If base year expenses were $8.00 per square foot and next year’s are $8.75, you pay your share of the $0.75 increase.
The trap is timing. If your base year happens to be abnormally low, maybe because the building was newly constructed or taxes hadn’t yet been reassessed, you’ll pay higher escalations for the rest of the term. Ask whether the base year will be restated if it proves abnormally low.
Expense Stop
An expense stop works like a base year but uses a fixed dollar amount per square foot instead of actual historical costs. The landlord absorbs expenses up to the stop; you pay your pro rata share of anything above it. If the stop is $9.00 and actual expenses come in at $10.25, you pay your share of the $1.25 overage. The threshold is a known number from day one, but landlords tend to set stops conservatively, so overages can start sooner than they would under a base year.
Reconciliation and Audit Rights
Operating expenses shift throughout the year, so landlords bill pass-throughs monthly based on estimates. At the end of the fiscal year, the landlord reconciles: they total the actual expenses and compare them against the estimated payments collected. If you overpaid, you’re owed a credit; if actual costs ran higher, you owe a lump-sum true-up. Those payments can be substantial, so keep a reserve, especially in the first year when estimates are least reliable.
Audit rights are the safeguard. A well-negotiated lease lets you inspect the landlord’s books after the annual reconciliation. That’s where tenants find misallocated costs, capital expenditures classified as CAM, management fees exceeding the lease cap, or expenses from unrelated properties added to your building’s total. If the lease doesn’t include an audit right, negotiate one in.
Rent Escalation
Net rent doesn’t stay flat. Nearly every commercial lease includes an escalation clause that raises the base rent at set intervals, usually annually. Three methods dominate:
- Fixed increases. Rent rises by a set dollar amount or percentage each year, such as 3% annually. Simple, and you can model the full term from day one.
- CPI-based increases. Rent adjusts based on changes in the Consumer Price Index, so escalations track actual inflation. The Bureau of Labor Statistics recommends the U.S. City Average CPI for escalation agreements. In low-inflation years this works in your favor; in high-inflation years it doesn’t.1Bureau of Labor Statistics. How to Use the Consumer Price Index for Escalation
- Fair market value resets. Rent resets to the prevailing market rate at specified intervals, often every five years. Neither party knows the future rate at signing, so this carries the most uncertainty.
If your lease uses CPI escalation, check for a floor (a minimum increase regardless of CPI) or a cap (a maximum). A 2% floor with a 5% cap means rent rises at least 2% even in a flat year but never more than 5% in a spike. If no cap is included, negotiate one.
Building Your True Occupancy Cost
Your total occupancy cost is the sum of net rent, estimated pass-throughs, escalations, and the annual reconciliation adjustment. Building that number before you sign means gathering a few figures:
- Net rent per rentable square foot. Confirm whether the quoted rate uses rentable or usable square footage, and apply the load factor if needed.
- Estimated pass-throughs. Ask the landlord for the current year’s actual operating expenses broken down by taxes, insurance, and CAM, then apply your pro rata share.
- Escalation projections. Model rent increases over the full term using the escalation method in the lease. For CPI, assume a reasonable inflation rate and run a high scenario too.
- Reconciliation buffer. Set aside a reserve for the annual true-up, especially in year one.
Add those together and you have a number you can compare across properties, even when one is quoted gross and another NNN. The NNN listing will always look cheaper at first glance because the net rent is lower. Once you layer in the pass-throughs, the gap often narrows. Run the full calculation for every space you’re considering; the listing price alone tells you very little about what you’ll actually spend.