NNN vs. Gross vs. Modified Gross Lease: What Changes in Abstraction
How lease structure affects what you extract and how you calculate it — for real estate professionals and developers abstracting commercial leases.
Lease structure determines which party pays operating expenses and, as a result, determines what data fields matter most in the abstraction. A gross lease abstract focuses on base rent because operating expenses are landlord's problem. A triple-net abstract needs the operating expense structure, CAM caps, exclusions, and reconciliation provisions because tenants pay most operating costs and need to budget for them.
Getting the lease type wrong in your abstraction is a common error that leads to incorrect expense projections, incorrect ASC 842 / IFRS 16 calculations, and portfolio reporting that doesn't reflect actual cash flows.
The Three Primary Lease Structures
Gross Lease (Full Service)
Landlord pays opexThe tenant pays a single monthly rent figure that includes all operating expenses — taxes, insurance, maintenance, utilities, and janitorial. The landlord absorbs the variability in operating costs. Common in multi-tenant office buildings and some retail.
Key abstraction fields:
- • Base rent (total — no additional expense components)
- • Any tenant-paid utilities (often excluded even in gross leases)
- • Any expense pass-throughs (janitorial, overtime HVAC)
- • Rent escalation schedule
- • Exclusions from “gross” coverage (important — gross leases are not all identical)
Triple Net (NNN)
Tenant pays opexThe tenant pays base rent plus three expense categories: property taxes, property insurance, and maintenance/CAM. The “net” in NNN means net of these costs to the landlord. True NNN leases are most common in single-tenant retail (freestanding) and industrial properties where tenants effectively control the property. Tenant total occupancy cost = base rent + taxes + insurance + maintenance.
Key abstraction fields:
- • Base rent (separate from operating expenses)
- • Which operating expense categories are tenant's responsibility
- • Whether expenses are estimated and reconciled or paid directly
- • Any CAM caps (important for tenant budget projections)
- • Exclusions from tenant's expense obligation (capital expenses, management fees, etc.)
- • Reconciliation process and timing
- • Audit rights for operating expense statements
Modified Gross
Split responsibilityModified gross is a hybrid: the tenant pays base rent plus some (not all) operating expenses. The specific split varies by lease. A common modified gross structure: tenant pays base rent plus electricity; landlord pays taxes, insurance, and maintenance. Another: tenant pays base rent plus operating expense increases above a base year stop. “Modified gross” is not a standardized term — you must read the expense provisions carefully to understand the actual split.
Key abstraction fields:
- • Which specific expenses the tenant pays (must be explicit)
- • Base year or expense stop (if expense increases are passed through)
- • Base year gross-up provision (important for accuracy)
- • CAM caps and exclusions on any passed-through expenses
- • Tenant utility responsibility (metered separately or included)
The Base Year Problem
Many office leases use a base year expense stop — the tenant pays their pro-rata share of operating expense increases above the base year's actual expenses. This requires abstracting the base year carefully:
- What year is the base year? Often the first full calendar year of occupancy, but sometimes a different year specified in the lease.
- Is the base year grossed up? If the building was not fully occupied in the base year, actual expenses may have been artificially low. Many leases specify that the base year shall be “grossed up to full occupancy.” If not abstracted, tenants may face unexpectedly high expense pass-throughs.
- What expenses are included in the base year calculation? Exclusions matter — management fees, capital expenditures, ground rent — all affect the base against which future increases are measured.
Impact on ASC 842 / IFRS 16 Calculations
Lease structure directly affects what you include in the lease payment stream for accounting purposes. Under both standards:
- Gross lease: The full base rent is included in the lease payment stream (it's not separable). Right-of-use asset and liability are based on total rent.
- NNN with fixed expense estimates: If expense estimates are fixed amounts (not variable based on actual costs), they may be included in the lease payment stream.
- NNN with variable expenses: Truly variable operating expenses (actual taxes, actual insurance) are excluded from the lease liability calculation and expensed as incurred.
- Modified gross with base year stop: The base rent is in the payment stream; the variable expense pass-throughs above the stop are not (they're variable).
Getting this wrong produces a different ROU asset and lease liability than the standard requires. On a 100,000 RSF office lease at $40/RSF gross, the difference can be millions of dollars in balance sheet impact.
Summary: What to Abstract by Lease Type
| Field | Gross | NNN | Modified Gross |
|---|---|---|---|
| Base rent | ✓ (all-in) | ✓ (net only) | ✓ |
| Expense categories (tenant-paid) | Sometimes | ✓ (all three nets) | ✓ (specific list) |
| Base year / expense stop | No | No | ✓ (if applicable) |
| Base year gross-up provision | No | No | ✓ |
| CAM caps and exclusions | Rarely | ✓ | ✓ (if applicable) |
| Reconciliation process | No | ✓ | Sometimes |
| Tenant utility responsibility | Sometimes | ✓ | ✓ |
LeaseIQ identifies lease type automatically
LeaseIQ reads the expense provisions of any commercial lease, classifies the structure (gross, NNN, modified gross, ground lease), and extracts the appropriate expense fields for each type. The output includes clear identification of what the tenant pays versus the landlord, with source citations.
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