Commercial Lease Types: Gross, Net, NNN, Modified-Gross, and Percentage Leases Explained

Commercial leases aren't standard forms. They're negotiated documents where the lease type sets the fundamental economic framework for who pays what over the term. Understanding each type means understanding the expense allocation logic, not just the label.

The Spectrum of Commercial Lease Types

Think of commercial lease types as a spectrum from full landlord responsibility to full tenant responsibility for operating expenses.

Gross Lease

A gross lease bundles all occupancy costs into a single rent figure. The tenant writes one check; the landlord handles property taxes, building insurance, utilities, janitorial, landscaping, and all maintenance.

How it works operationally: The landlord underwrites estimated operating costs when setting base rent. A property running $9/SF in annual operating expenses might set gross rent at $24/SF to achieve a $15/SF net rent. If operating costs rise to $11/SF, the net margin compresses to $13/SF. The landlord absorbs the loss.

Where gross leases appear: Small office suites, flex space, properties in soft markets where landlords need to compete on simplicity, short-term occupancies. Less common in institutional-grade retail and industrial.

The landlord's pricing risk: Gross leases require accurate operating cost forecasting over the lease term. Underpricing by $2/SF on a 30,000 SF building is $60,000/year in compressed NOI. Many landlords add annual escalations (2–3% CPI bumps) to gross rent to hedge against cost increases.

No CAM reconciliation: This is the major operational difference. No estimates, no year-end true-up, no audit rights. Simpler for both parties, at the cost of expense recovery flexibility.

For a direct comparison, see gross lease vs net lease and NNN lease vs gross lease.

Modified-Gross Lease (Base Year / Expense Stop)

Modified-gross leases split operating expenses at a threshold: the landlord pays up to the base year level, the tenant pays any increases above it. The threshold is established either as:

• Base year: Actual operating expenses in the lease commencement year (or a specific defined year)
• Expense stop: A negotiated per-SF dollar amount above which the tenant pays

How it works operationally: Suppose the base year is 2024 and actual operating expenses were $13.20/SF. In 2026, actual operating expenses are $15.40/SF. The tenant owes $2.20/SF as an operating expense escalation, billed through annual reconciliation.

The reconciliation requirement: Modified-gross leases require the same annual expense tracking as NNN leases. The landlord must compile actual expenses, compare to the base year benchmark, calculate each tenant's share of overages, and issue statements. The only mechanical difference from NNN reconciliation is the presence of a floor. Learn more about CAM reconciliation to understand the process.

Common in office: Modified-gross with base year is the dominant structure in Class A and B office nationwide. The base year timing matters a lot. A 2020 base year is favorable for tenants (low occupancy during COVID depressed some costs); a 2023 base year is more neutral.

Negotiation points: Which expenses are included in the base year calculation? Management fees, leasing commissions, and one-time capital costs are sometimes excluded. Does the base year gross up to stabilized occupancy? Some landlords insist on grossing the base year to 95% occupancy to prevent tenants from benefiting from low base-year costs due to partial occupancy.

Single-Net Lease (N Lease)

Single-net leases pass property taxes to the tenant; the landlord retains all other operating cost responsibility. The tenant pays base rent plus their pro-rata share of property taxes, billed as a separate line item or built into rent.

How it works: Property tax bills are typically paid by the landlord, then allocated to tenants based on their pro-rata share of the building's assessable value or square footage. Some single-net structures have the tenant pay taxes directly to the municipality, though this is less common in multi-tenant settings.

Rare in modern CRE: Single-net leases are uncommon in contemporary commercial real estate because the expense split is awkward. The landlord retains significant risk (insurance, maintenance, CAM) while the tenant pays the single most volatile line item (property taxes). Neither party benefits clearly from this allocation.

Where you still see them: Older industrial leases, some ground leases, legacy retail arrangements. When you encounter one in due diligence, understand that any operating cost increases beyond property taxes sit with the landlord. See single-net lease explained for the full analysis.

Double-Net Lease (NN Lease)

Double-net leases pass property taxes and building insurance to tenants. The landlord retains responsibility for structural maintenance, roof, foundation, and major building systems.

How it works: Taxes and insurance are billed annually, either as actual costs (common) or as estimated monthly amounts with year-end reconciliation. CAM (parking lot, landscaping, janitorial) stays with the landlord in a standard double-net arrangement, though some NN leases also pass certain CAM categories.

The structural maintenance question: What exactly is "structural"? Well-drafted NN leases define this precisely: foundation, exterior walls, roof structure and membrane, major mechanical systems. Poorly drafted leases leave gray areas that become disputes: is HVAC a major building system or a maintenance item?

Who uses NN leases: Regional retail properties, some older suburban office, industrial properties where the landlord retained certain maintenance obligations. Less common than NNN in institutional-grade properties. See double-net lease explained for the complete breakdown.

Triple-Net Lease (NNN)

NNN leases are the standard for modern retail and industrial CRE. Tenants pay base rent plus property taxes, building insurance, and all operating/maintenance expenses including CAM. The landlord typically retains only structural and foundation responsibility, and even that varies by negotiation.

The CAM reconciliation cycle: NNN leases require a complete annual CAM reconciliation. The process:

1. Landlord estimates operating expenses for the coming year, broken down by category
2. Monthly estimates are billed to each tenant based on pro-rata share
3. At year end, actual expenses are compiled and compared to estimates
4. Tenants receive a statement showing actual vs. estimated: overage requires true-up payment, underage generates credit

The CAM true-up is the year-end settlement that closes out this cycle. The pro-rata share calculation determines each tenant's allocation.

Common NNN inclusions:

• Janitorial services (common areas only)
• Landscaping and exterior maintenance
• Parking lot maintenance and resurfacing
• Lighting and electrical (common areas)
• Property management fees (typically 3–5% of gross revenues)
• Security
• Trash removal
• Insurance premiums
• Property taxes

Common NNN exclusions (negotiated):

• Capital expenditures (or amortized over useful life)
• Leasing commissions and legal fees
• Debt service
• Ground rent
• Costs of work done for other tenants' benefit
• Depreciation
• Anchor tenant exclusions

See what is included in CAM expenses and the CAM exclusion list complete guide for the definitive breakdown.

Controllable vs non-controllable caps: Most NNN leases now cap controllable expense increases at 3–5% annually. Non-controllable expenses (taxes, insurance) pass through without a cap. The controllable vs non-controllable expenses guide explains how this distinction is applied in practice.

Gross-up provision: In multi-tenant buildings, variable expenses are typically grossed up to 90–95% occupancy to normalize costs across tenants. The CAM gross-up calculation guide covers the mechanics.

Percentage Lease

Percentage leases add a variable revenue-sharing layer on top of a base structure (which itself may be NNN or modified-gross). They're almost exclusively retail.

The breakpoint calculation:

Natural breakpoint = Annual base rent ÷ Percentage rate

If a tenant pays $84,000/year in base rent and the lease specifies 7% of gross sales:

• Natural breakpoint = $84,000 ÷ 0.07 = $1,200,000
• Sales above $1.2M: tenant pays 7% of the excess

Artificial breakpoints are negotiated lower than natural, meaning the percentage rent kicks in at lower sales volume. Landlords prefer artificial breakpoints; tenants prefer natural.

Percentage rent + NNN: Most percentage leases in modern shopping centers combine percentage rent with NNN operating expense pass-through. A tenant might pay $18/SF base rent (NNN), percentage rent above a $2.5M breakpoint at 5%, plus monthly CAM estimates. All three are separate line items reconciled annually.

Sales reporting and audit: Landlords have the right to audit tenant gross sales reports under percentage lease provisions. This is separate from CAM audit rights but happens at the same property level. Tenants must maintain sales records and report monthly or quarterly gross sales figures.

Hybrid and Specialty Structures

Real-world leases rarely fit neatly into textbook categories. Common hybrids:

Absolute NNN (Bond Net): Tenant pays everything, including structural and roof. Landlord's only obligation is to hold title. Common in single-tenant NNN investment properties (banks, pharmacies, fast food). See NNN investment properties CAM analysis.

Modified NNN with gross lease elements: Some leases combine NNN pass-throughs for taxes and insurance with a landlord CAM cap or fixed CAM contribution. The landlord effectively takes a gross position on CAM while passing through the more volatile items.

Ground lease with improvement lease: Ground leases (landlord owns land, tenant owns building) typically have the tenant pay all ownership costs including taxes, insurance, and maintenance on the improvements. These are absolute net by nature.

Choosing the Right Structure: A Decision Framework

For tenants, the analysis runs in reverse: the more expense pass-through in the lease, the more important it is to understand what's actually included in the CAM pool, what caps protect you, and what audit rights you have.

The commercial lease rent structures guide has worked examples for each structure type. For the NNN vs. gross financial comparison over a full lease term, see NNN lease vs gross lease.

CAM Software for Multi-Structure Portfolios

Managing a portfolio with multiple lease types simultaneously (common during lease rollover periods) requires tracking different expense pass-through rules for different tenants in the same building. A gross lease tenant next to a NNN tenant creates two parallel accounting tracks.

CapVeri's reconciliation engine handles multi-structure portfolios by mapping each tenant's lease terms to the correct expense pass-through logic. The system applies base year stops where applicable, gross-up to the right tenants, and flags when actual billing deviates from lease-defined inclusions. The best CAM software 2026 guide covers what to look for in a reconciliation platform.

Sources

1. ICSC - Dictionary of Shopping Center Terms
2. J.P. Morgan - What Are CAM Charges in CRE?