CAM Overcharge: The Complete Guide for Commercial Tenants
Most commercial tenants pay CAM — Common Area Maintenance, also billed as "additional rent," "operating expenses," or "NNN" — without ever checking the math. That's where overcharges hide. Material errors in CAM reconciliations are common, and a single bad number (your share, the building size, a line item that doesn't belong) can quietly cost a small tenant thousands a year. This guide maps the most common CAM overcharge mechanisms, links to a deep-dive on each, and shows how to cross-check your own bill.
What is a CAM overcharge?
A CAM overcharge is any amount your landlord passes through to you that exceeds what your lease actually allows — whether because your pro-rata share is computed on the wrong denominator, a non-recoverable cost was folded in, a capital improvement was billed as an operating expense, or a gross-up was misapplied. It isn't always fraud; most are reconciliation errors. Either way, the dollars are real, and the lease usually gives you a window to ask for the backup. Start with the basics in what "additional rent" (NNN / CAM) actually is and how to read your CAM reconciliation statement.
1. Your pro-rata share and the building denominator
Your CAM bill is your share of the building's costs — your space ÷ the building's total size. Shrink that denominator (understate the building) and every tenant's share silently inflates. The denominator is the single most valuable number to check, because an error there scales across your whole bill. Full mechanism: your pro-rata share — the most common CAM overcharge. A real-world example of denominator inflation is the Uniqlo v. Gazit $450K dispute.
2. Gross-up clauses applied incorrectly
A gross-up clause adjusts variable costs as if the building were ~95–100% occupied, so a tenant in a half-empty building isn't undercharged. Misapplied — grossing up fixed costs, or above the occupancy cap — it inflates a small tenant's share. See gross-up in CAM charges, explained.
3. Costs that can't legally be in CAM
Standard commercial leases exclude whole categories from CAM: capital improvements, leasing commissions, landlord overhead, costs reimbursed by insurance. When they show up anyway, that's a recoverable error. See what can't legally be in your CAM charges and the broader phantom CAM fees and lease escalation patterns.
4. Year-over-year spikes and the surprise true-up
CAM is usually estimated monthly and reconciled once a year — which is why a year-end "true-up" can land as a surprise bill. Most operating costs rise ~3–5% a year, so a category that jumps 15–20% (or exceeds your lease's annual cap) is worth questioning. See why you got a surprise year-end CAM bill and 5 ways landlords overcharge CAM.
5. The same error, multiplied across locations
If you operate multiple stores, a small per-location CAM error compounds across the portfolio — and the same denominator/gross-up mechanisms apply at every building. See multi-location merchants: you may be overpaying CAM at every store.
How do I check whether I'm being overcharged?
You cross-check the numbers you were billed against your lease and against independent public data — county building-size records for the denominator, the landlord's own REIT filings, and BOMA cost benchmarks. That's a CAM cross-check, and you can do the first pass free. The full method is in how to verify your CAM charges with public records. California small-business tenants have extra leverage under SB-1103.
Start the free CAM cross-check →
Informational only; not legal advice and not an audit or attest service. ReCAM is not a CPA firm and these services are not regulated by any state board of accountancy. © ReCAM Technologies LLC.