Your landlord sends you an annual CAM reconciliation statement. It shows total building operating expenses for the year, your pro-rata share, and either a bill for the shortfall between your actual share and your monthly estimates, or a credit if you overpaid. In most commercial leases, you have between 30 and 90 days to pay any balance due.
What many tenants do not realize: that statement is self-reported. The landlord prepared it, often with minimal documentation, and the assumptions embedded in it — which expenses are included, how the building is measured, what management fee was charged — directly affect how much you owe. Independent audits of CAM statements consistently find overcharges. Understanding how to conduct your own audit, or how to evaluate the work of an audit firm, protects money that is rightfully yours.
Your Lease Is the Control Document
Before reviewing any expense figures, pull your executed lease and every amendment. The CAM provisions in your specific lease govern what can be charged, not industry norms or what the landlord's form says was "standard practice." You are auditing against a contract.
The key provisions to locate and understand before you start:
CAM exclusions list. Most negotiated leases include a list of expense categories the landlord cannot include in CAM. Common exclusions: capital expenditures and depreciation, leasing commissions and costs of procuring new tenants, costs of renovating vacant space, landlord's income taxes, costs covered by insurance proceeds, and expenses attributable to other tenants' negligence. If your lease has an exclusions list, any expense in an excluded category is a potential overcharge.
Management fee cap. Many leases cap the management fee at a percentage of gross revenues (typically 3-5%). If the landlord charged a management fee — and most do — verify it against the cap. Management fee overcharges are common because landlords sometimes charge a market-rate fee on top of their actual overhead costs.
CAM cap provision. Some leases cap annual increases to controllable CAM expenses. If your lease has a CAM cap, the year-over-year increase in the applicable expense categories cannot exceed the cap regardless of actual expense increases. Caps on controllable expenses typically exclude taxes, insurance, and utilities.
Pro-rata share definition. Your lease states how your pro-rata share is calculated — typically your leased square footage divided by total building square footage. Verify that both numbers match the lease. Errors in square footage are a consistent source of overcharges.
Gross-up provision. If your building is not fully occupied, some leases allow the landlord to gross up variable operating expenses to 100% occupancy for purposes of the CAM calculation. This protects fully-occupying tenants from bearing more than their fair share in a partially-occupied building. But it can also inflate the expense pool if applied incorrectly or if expenses that are not truly variable are grossed up.
The Audit Process Step by Step
Step 1: Obtain the CAM statement and request backup documentation. Most leases give tenants the right to request supporting documentation — the landlord's actual invoices, contracts, and expense ledgers. Exercise this right in writing, citing the specific lease provision. Document the date of your request and the deadline for the landlord's response.
Step 2: Reconcile total expenses against the expense categories. The CAM statement should list expenses by category. Total them yourself and confirm they match the statement's total. Basic arithmetic errors occur more than you would expect.
Step 3: Check each expense category against your exclusions list. Go line by line. If the statement shows a "roof replacement" expense and your lease excludes capital expenditures, that is a disputed item. Document each item that conflicts with your exclusion list.
Step 4: Verify the management fee. Identify the management fee line item and calculate it as a percentage of the gross revenue figure the landlord used. Compare against your lease's cap. If the landlord charged 5% and your lease caps it at 3%, you have found an overcharge on that line.
Step 5: Verify the pro-rata share calculation. Confirm your leased square footage against the lease. Then verify the denominator — the total building square footage. Some landlords use only rentable area (excluding common areas that benefit all tenants), some use gross building area, and some use definitions that vary from the lease's own language. Verify against the lease definition, not whatever figure the landlord uses.
Step 6: Review the gross-up calculation, if applicable. If your lease allows gross-up and the landlord applied it, verify that only variable expenses were grossed up and that the gross-up calculation uses actual occupancy data for the period, not an estimate. Ask for the occupancy schedule supporting the calculation.
Step 7: Apply the CAM cap, if applicable. Calculate the maximum allowable increase in controllable expenses using your lease's cap formula. Compare against the actual increase in the statement. If the actual increase exceeds the capped amount, the excess is not billable.
The Five Most Common Overcharges
Field experience across thousands of CAM audits shows the same overcharges appearing repeatedly.
Capital expenditures billed as operating expenses. Roof replacements, HVAC system replacements, parking lot repaving, and elevator modernizations are capital improvements — they extend the useful life of the building and should be capitalized, not expensed in a single year. Landlords sometimes characterize these as repairs and maintenance and include them in CAM. The distinction between a capital improvement and a repair is sometimes genuinely ambiguous, but clear capital replacements should be excluded.
Management fees over cap. As noted above, management fee caps are frequently violated. This is one of the most productive places to look in any audit because the dollar amounts are significant (management fees on a multi-million-dollar expense pool can be hundreds of thousands of dollars) and the overcharge calculation is straightforward.
Excluded items included. Leasing commissions, costs of tenant improvements in vacant space, and landlord's administrative overhead are excluded by name in many leases but still show up in CAM statements. Sometimes the expenses are buried in broader categories (a leasing commission classified under "professional services") rather than appearing as a distinct line item.
Incorrect building square footage. If the denominator in your pro-rata share calculation is wrong — either because the landlord is using a different measurement standard than the lease requires or because the building's rentable area changed due to expansions or re-measurements — your share is wrong. Errors of 2-5% in building square footage are common and produce proportional errors in your CAM charges every year.
Improper gross-up calculation. When landlords apply the gross-up to expenses that are not variable, they inflate the recoverable expense pool. Janitorial and utilities scale with occupancy; property taxes and insurance do not. A landlord who grosses up taxes is charging you for hypothetical tax expenses that were never incurred.
Exercising Your Audit Rights
Your lease's audit rights provision specifies: the notice required to initiate an audit, the time period within which an audit must be completed, whether the audit must be conducted by a CPA or other qualified professional, how disputes are resolved, and who pays for the audit if overcharges exceed a threshold.
Initiate an audit in writing, following the notice requirements exactly. Landlords sometimes try to deny audits on technical grounds (wrong form of notice, wrong addressee, untimely request), so document your compliance with each procedural requirement.
If your lease does not have an audit rights provision — or if the audit right has expired — you still have remedies if the landlord made a material misrepresentation in the reconciliation. But your leverage is significantly reduced. This is a provision worth negotiating carefully in the original lease.
Most CAM overcharges are not the result of fraud. They are the result of landlords applying their standard accounting practices without careful attention to each tenant's specific lease provisions. A systematic audit — lease in hand, line by line — recovers money that the lease entitles you to.