A Gross lease charges one flat monthly rent and the landlord pays the operating expenses; a Triple Net (NNN) lease charges a lower base rent plus the tenant's pro-rata share of property taxes, building insurance, and Common Area Maintenance (CAM). The headline NNN base rent looks cheaper, but the all-in cost can be higher once the pass-throughs are added — for example, a $15/sqft NNN deal can cost more than a $22/sqft gross deal in the comparison worked below.

This guide explains both structures, the Modified Gross middle ground, the base-year mechanic that catches tenants off guard, and the specific clauses to negotiate before signing.

TL;DR — at a glance

| Structure | Tenant pays | Predictable? | Where you see it | |---|---|---|---| | Full Service Gross | One flat rent (everything included) | Yes | Class-A office, some flex spaces | | Modified Gross | Flat rent + utilities and janitorial; landlord covers taxes/insurance/CAM | Mostly | Mid-tier office, professional services | | Industrial Gross / "Base Year" | Flat rent at signing; tenant pays expense growth above a base-year number | Partially | Multi-tenant office | | Triple Net (NNN) | Base rent + pro-rata taxes + insurance + CAM | No (CAM fluctuates) | Retail, industrial, single-tenant build-to-suit | | Absolute Net | Everything, including roof and structural | No | Single-tenant industrial, ground leases |

What is a Gross lease?

In a Full Service Gross lease the tenant pays one flat amount per month — Cornell's Legal Information Institute describes a gross lease as one where "the landlord includes maintenance fees, taxes, and other expenses in their calculation of the rent" (LII Wex: gross lease). The landlord pays for and absorbs:

Property taxes
Building insurance
Common Area Maintenance (CAM) — landscaping, snow removal, parking lot upkeep, common-area utilities
Building HVAC, roof, and structural repairs
Sometimes in-suite utilities and janitorial (when the lease is genuinely "full service")

The advantage is budget predictability. You know exactly what hits the bank account each month. The disadvantage is that landlords build the expected operating expenses into the rent — and pad them — so a gross rent number is always going to look higher than an NNN base rent on a comparable space.

Gross leases are traditionally associated with office and professional-service buildings where the landlord wants to compete on simplicity.

What is a Modified Gross lease?

Modified Gross is the middle ground. The tenant pays a flat rent plus some — but not all — of the operating costs. The most common variant is:

Tenant pays in-suite utilities, in-suite janitorial, and after-hours HVAC overrides.
Landlord pays taxes, insurance, CAM, and structural items.

The cost-allocation lines are negotiable; insist that the lease enumerate exactly which expenses are tenant-paid and which are landlord-paid. Loose language like "tenant pays its share of operating costs" without an itemized definition is a classic CAM trap — it lets the landlord reclassify capital improvements as operating costs and pass them through.

What is a Triple Net (NNN) lease?

In a Triple Net (NNN) lease the tenant pays a base rent plus all three "nets" — Cornell's LII defines a triple net lease as one where the tenant "pays rent and utilities as well as three other types of property expenses: insurance, maintenance, and taxes" (LII Wex: triple net lease):

Net — Property taxes
Net — Building insurance
Net — Common Area Maintenance (CAM) / operating expenses

Each "net" is charged as the tenant's pro-rata share — your square footage divided by the building's total rentable square footage, times the relevant expense. Some leases also pass through utilities, management fees, and an administrative markup on top of CAM.

NNN leases are the dominant structure in retail, industrial, and single-tenant build-to-suits — Cornell's net-lease overview notes the triple net is the most prevalent net-lease type, especially for single-tenant buildings (LII Wex: net lease) — because they let the landlord lock in a predictable yield while shifting cost volatility to the tenant. The tenant gets a lower headline rent in exchange for taking on the operating risk.

Why low base rent is a trap

Here is the trap: landlords advertise a low base rent to lure tenants in, and the all-in occupancy cost is far higher once NNN is added. Compare two leases for a 2,000-square-foot retail unit:

Deal A — Modified Gross

Base rent: $22/sqft → $44,000/year → $3,667/month
Tenant pays utilities and janitorial: ~$400/month
All-in: ~$4,067/month

Deal B — Triple Net

Base rent: $15/sqft → $30,000/year → $2,500/month
NNN charges: $8/sqft → $16,000/year → $1,333/month (taxes $3/sqft + insurance $1/sqft + CAM $4/sqft)
Tenant pays utilities and janitorial: ~$400/month
All-in: ~$4,233/month

The NNN deal looks cheaper at $15 vs. $22 — but the all-in cost is $166/month higher ($2,000/year, $10,000 over a five-year term). And the NNN number is the estimate at signing. CAM is reconciled annually against actual expenses; in a year with a roof replacement, a property-tax reassessment, or a new property manager, the tenant gets a true-up bill for thousands of dollars they didn't budget for.

Always compare the all-in occupancy cost (rent + pass-throughs + utilities) per square foot — never the base rent alone. Tools like the Triple Net (NNN) Calculator exist to do this comparison consistently.

Base year leases — the middle-of-the-road option

A Base Year lease (sometimes called Industrial Gross or Office Gross) is a hybrid. The tenant pays a flat rent at signing; the landlord absorbs all operating expenses up to a "base year" benchmark. The tenant only pays the growth in operating expenses above the base year going forward.

The mechanics seem tenant-friendly, but two specific clauses can ruin them:

Gross-up clauses — if the building is less than fully occupied during the base year, the landlord "grosses up" expenses to what they would have been at full occupancy. This inflates the base year (good for the tenant) — but tenants should require the gross-up be applied consistently in every reconciliation year, not selectively.
Expense stops — instead of the tenant's base year, the landlord sets a fixed dollar amount per square foot ("expense stop") above which the tenant pays the growth. If the stop is set artificially low, the tenant pays pass-throughs from year one.

Read the Operating Expenses / CAM clause guidance before signing any base-year deal.

When each structure favors the tenant vs. the landlord

| Scenario | Best structure for tenant | |---|---| | Short-term lease (1–3 years) | Gross or Modified Gross — minimizes surprise reconciliations | | Stable, predictable operating costs (Class-A office, low CAM) | Gross | | Variable CAM exposure (retail strip with active reinvestment) | Avoid NNN; if forced, demand a CAM cap | | Newly built or recently renovated property | Negotiate aggressively — CAM should be low early in the life of the building | | Tenant has strong balance sheet, wants to control its own occupancy costs | NNN can be advantageous if the tenant is willing to audit and manage CAM actively |

Landlords prefer NNN because it shifts cost volatility off the rent roll. Sophisticated landlords will also try to convert a Modified Gross lease into NNN at renewal — watch for renewal language that "trues up" the lease to market structure.

Key clauses to negotiate in any NNN deal

CAM Cap — Limit annual CAM increases to a fixed percentage (for example, 4–5%) over the prior year, with carve-outs for uncontrollable items like property tax growth. A cap on controllable CAM is a reasonable demand — even Cornell's LII flags unforeseen maintenance costs and tax increases as the core NNN tenant risk unless the parties agree to cap them (LII Wex: triple net lease).
Capital Expenditure Exclusion — Roof replacement, HVAC unit replacement, parking-lot resurfacing, and major structural repairs should be landlord costs, not CAM pass-throughs. The line between "repair" and "replacement" is where most NNN disputes happen — see the roof and HVAC replacement guide.
CAM Reconciliation + Audit Rights — The lease should require an itemized annual statement comparing budget to actual, with the tenant having the right to audit the landlord's books (often negotiated as tenant-paid unless the audit reveals an overcharge above an agreed threshold — e.g., 5%).
Management Fee Cap — Limit the landlord's administrative markup on CAM (for example, 3–5% of operating expenses, not a flat fee).
Exclusions list — Spell out what is NEVER in CAM: capital improvements, leasing commissions, marketing, legal fees from other tenant disputes, landlord-side property management, depreciation, ground rent, lender fees. Without an exclusions list, landlords pass these through.
Base Year Reset Protection — If you're in a base-year deal and renew, negotiate that the base year resets to the renewal year, not stays frozen at the original base year (which would compound your exposure to ~6+ years of expense growth at renewal).

Quick decision framework

Before signing, ask:

What is my all-in cost per square foot? (Base rent + estimated NNN + utilities + parking + insurance + tenant taxes.)
What does "estimated NNN" actually include? Get the landlord's CAM budget in writing and ask for the prior-year actuals.
What happens if CAM goes up 50% next year? If the answer is "you pay all of it", insist on a cap. If the answer is "we share it through a base-year mechanic", make sure the gross-up clause is fair.
Am I responsible for any capital expenditure? If yes, narrow the language to specific items and amortize anything over $X (say, $25,000) across the useful life of the improvement so you only pay your fair share.
Can I audit? A landlord who refuses to give you audit rights is telling you something.

How BizLeaseCheck helps

BizLeaseCheck reads your lease in seconds and flags whether it's NNN, Modified Gross, or Full Service — and surfaces every clause that affects your pass-through exposure. The report identifies missing CAM caps, missing audit rights, vague expense exclusions, and any language that lets the landlord reclassify capital improvements as operating expenses. See a sample report or upload your lease to get a free preview.

Not legal advice. Use the report to flag issues for discussion with qualified counsel — particularly on multi-year leases where the cumulative pass-through exposure can run into six figures.

Triple Net (NNN) vs. Gross Leases: The Tenant's Cost-Comparison Guide