CAM Reconciliation for Office Buildings: What's Different and What to Watch For
Office CAM reconciliation is structurally different from retail or industrial — dominated by interior costs, complicated by modified gross lease structures, and facing a unique gross-up challenge in a post-2020 high-vacancy market. Here is what office landlords need to get right.
By Angel Campa, Founder, CapVeri · Updated April 2026
Quick Answer
Office building CAM differs from retail and industrial primarily in the expense composition (HVAC dominates at 25–35% of CAM), the lease structure (modified gross leases are common — fewer pass-throughs than NNN), and the occupancy dynamics (19–20% national vacancy in 2026 creates significant gross-up complexity that most office landlords are under-applying).
Office CAM Expense Profile
Understanding what drives office CAM costs is the starting point for reconciliation. Unlike retail (exterior-dominated) or industrial (minimal common area), office CAM is predominantly interior maintenance.
| Expense Category | % of Total CAM | OpEx or CapEx? | Key Reconciliation Issue |
|---|---|---|---|
| HVAC (common areas) | 25–35% | OpEx (maintenance); CapEx (replacement) | Separating maintenance from capital work |
| Janitorial | 20–30% | OpEx | Common area only — not tenant suites |
| Utilities | 15–25% | OpEx | Sub-metering of tenant vs. common area |
| Security / concierge | 10–20% | OpEx | 24/7 vs. business hours staffing levels |
| Elevator maintenance | 5–10% | OpEx (service); CapEx (cab replacement) | Full modernization vs. maintenance contract |
| Parking / exterior | 5–15% | OpEx | Garage structure maintenance classification |
Modified Gross vs. Full NNN in Office
The majority of office leases — particularly for Class A and B properties — are modified gross leases, not full NNN. This distinction fundamentally changes what is recoverable and how the reconciliation works.
Full NNN Office Lease
Less common. Tenant pays all operating expenses above a base. Reconciliation covers all categories. Common in Class C properties, older suburban office parks, and sale-leaseback structures with sophisticated tenants.
Modified Gross Office
Most common. Base rent includes certain operating expenses (typically utilities, janitorial within suites). Only recoverable CAM above the base year stop is billed separately. The “modification” varies by lease.
When reconciling a modified gross lease, the first question is: what does the base rent include? If base rent includes utilities and janitorial for tenant suites, those categories may not appear in the CAM reconciliation at all. Misclassifying included vs. excluded expenses inflates the CAM pool and overbills tenants.
Base Year Mechanics: Why 2019 Is Problematic in 2026
A base-year lease sets the reference level for operating expenses. The tenant pays only the overage above the base. For leases where the base year was set in 2019, operating costs have risen 30–40% since then — meaning the landlord absorbs a substantial below-base-year expense pool and only recovers the increase.
Base Year Example
| 2019 base year operating expenses (per lease) | $12.00/SF |
| 2025 actual operating expenses | $16.50/SF |
| Recoverable from tenant (above base) | $4.50/SF |
| Landlord absorbs (at or below base) | $12.00/SF |
| Recovery ratio | 27% |
This is why office recovery ratios are lower than NNN — the base-year structure is designed to protect tenants from absorbing the full operating cost burden.
Some landlords attempt to negotiate “grossed-up base years” — adjusting the base year to reflect full occupancy — when renewing or extending leases. This can meaningfully change the above-stop amount.
The Vacancy Problem: Gross-Up in Office Buildings
National office vacancy was approximately 19–20% in early 2026. Many Class B markets exceed 25% vacancy. Under standard gross-up provisions, when occupancy falls below the lease threshold (commonly 90–95%), variable operating expenses should be grossed up to reflect what they would have been at full occupancy.
This is a critical protection for occupied tenants — without gross-up, they effectively subsidize the vacant space by paying a full pro-rata share of expenses that are distributed across only occupied square footage. But gross-up is under-applied in high-vacancy office environments.
Gross-Up Example: 75% Occupied Office
| Building: 100,000 RSF, 75% occupied (75,000 SF leased) | |
| Actual variable CAM (janitorial, utilities — usage-based) | $450,000 |
| Grossed up to 95% occupancy: $450,000 × (95,000 / 75,000) | $570,000 |
| Additional recoverable expense from gross-up | +$120,000 |
See the full gross-up guide for the complete mechanics, including which expenses are variable vs. fixed and how to document the gross-up calculation for tenant review.
What Can Go Wrong
Including HVAC capital replacements in the recoverable CAM pool
When a chiller or AHU is replaced, the capital cost may be coded to a maintenance GL account rather than a capital account. Unless it is caught in the expense classification review, it flows through to tenants as an operating expense — which it is not. This is among the most common office CAM audit findings.
Not applying gross-up when occupancy falls below 90%
In a 20%-vacant building, the failure to gross up variable expenses means occupied tenants pay less than they should (because the pool is smaller than it would be at full occupancy), and the landlord absorbs the difference. This is a recoverable revenue gap that compounds across years of high vacancy.
Applying the wrong base year in multi-term tenancies
When a tenant exercises a renewal option, the base year may reset to the first year of the renewal term — or it may stay fixed at the original base year. This depends entirely on the lease. Using the wrong base year (often the original one when the renewal reset it) systematically overbills tenants in renewal periods.
Frequently Asked Questions
What is included in office CAM charges?
Office CAM typically includes: HVAC for common areas (25–35% of CAM), janitorial for lobbies and corridors, elevator maintenance, security, common area utilities, and parking maintenance. It does not include HVAC replacements (capital), janitorial within leased suites, or tenant improvement costs.
What is a base-year lease and how does it affect office CAM reconciliation?
A base-year lease sets a reference year for operating expenses. The tenant pays only the overage above the base year level. For a 2019 base-year lease in 2026, the tenant might pay $4.50/SF in above-base CAM while the landlord absorbs the base $12.00/SF within the base rent.
Is HVAC maintenance an operating expense or a capital expense?
Routine HVAC maintenance contracts are operating expenses — recoverable through CAM. Major component replacements (compressors, AHUs, chillers) are capital expenditures. Some leases allow amortization of capital HVAC work over its useful life, in which case only the annual amortization is billed.
What is the typical CAM per SF for Class A office in 2026?
Class A office CAM runs $4–8/SF per year in 2026. Class B office ranges $3–6/SF. These figures have risen 20–30% from pre-2020 levels due to HVAC upgrades, security cost increases, and higher labor rates.
Related Resources
CAM Gross-Up Guide
How to apply gross-up provisions correctly in high-vacancy office buildings
Q1 2026 Office Vacancy & Gross-Up
Current vacancy rates and gross-up impact analysis
CAM Benchmarks by Property Type
Office CAM per SF benchmarks vs. retail and industrial
CAM Reconciliation Software
How CapVeri handles base-year mechanics and gross-up for office portfolios
Catch Office CAM Errors Before Tenants Do
CapVeri flags HVAC capital items in GL exports, applies gross-up automatically at the correct occupancy threshold, and validates base-year calculations against lease terms — for every tenant in your office portfolio.
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