How to audit CAM charges as a commercial tenant

Updated July 28, 2026

A CAM audit compares a landlord’s common area maintenance charges with the rules in a tenant’s commercial lease. Common area maintenance, usually called CAM, includes eligible costs of operating shared areas. The goal is to determine whether the billed amount follows the negotiated definitions, exclusions, caps, and allocation method.

The review can be organized into seven steps. Begin with timing because a correct analysis submitted too late may have little practical value.

Step 1: Know your audit window

Find the clause that governs annual statements, objections, and audit rights. Many leases limit how long after delivery of a reconciliation statement the tenant may dispute charges or request records. The period may run from receipt, not from the statement date.

Record the actual receipt date and compute the last day for action. Read the notice clause too. It may require written notice sent by a particular delivery method to specific addresses. Treat this date as the controlling project deadline and plan the review backward from it.

The lease may distinguish between asking questions, sending a formal objection, and conducting an inspection of records. Identify each available step and its timing.

Step 2: Assemble the documents

Collect the signed lease, every amendment, the current reconciliation statement, and the prior year’s statement for comparison. Include any correspondence that confirms changes to the premises area, property size, expense pools, or estimated payments.

Do not review the base lease alone. An amendment may change the pro-rata share, cap, payment method, or audit procedure. Build a short list of the currently governing CAM terms before checking the statement.

Ask for supporting detail if the statement is highly aggregated. A general ledger is the accounting record of individual transactions. Depending on the lease and process, useful support may include ledger detail, invoices, allocation schedules, and explanations for unusual changes.

Step 3: Verify the pro-rata share

The pro-rata share is the fraction of eligible property expenses allocated to the tenant. Recompute it from the definition in the lease. Confirm the tenant area, denominator, excluded spaces, and any separate pools for particular buildings or services.

Suppose the lease defines the share as 12,000 square feet of premises divided by a 100,000 square foot shopping center. The resulting share is 12 percent. If the statement bills 14 percent, the tenant pays an extra two percentage points of every dollar in the CAM pool. On $500,000 of eligible costs, that difference would be $10,000.

Check whether gross-up rules affect the calculation. A gross-up adjusts certain variable expenses to a specified occupancy level. It should apply only as the lease permits.

Step 4: Check the exclusions

Read each statement category against the lease’s exclusion language. Common subjects include capital replacements, structural work, leasing commissions, legal costs related to other tenants, debt service, depreciation, and costs reimbursed by insurance.

Labels alone are unreliable. “Repairs and maintenance” could contain routine work, a full equipment replacement, or both. Trace material or unusual amounts to the underlying detail and classify them under the lease’s own wording.

Also look for duplicate recovery. A cost should not appear in CAM if it was charged directly elsewhere or reimbursed from another source when the lease requires that reimbursement to be credited.

Step 5: Apply the caps

Identify which costs are controllable and which are uncontrollable under the lease. A controllable-cost cap limits increases in the expense categories the landlord can influence. Taxes, insurance, utilities, or weather-related costs may be outside the cap, depending on the agreement.

Recalculate the allowed amount from the correct base year. Determine whether the cap is cumulative, compounded, or applied year by year. Compare like categories across years because moving a cost between categories can distort the result.

Step 6: Check the arithmetic

Recalculate subtotals, fees, shares, credits, estimated payments, and the final true-up. Administrative fees should use the base allowed by the lease. Caps and exclusions should flow through before the tenant’s final charge is calculated when the agreement requires that sequence.

Every finding should sum exactly. If your corrected charge is $82,000 and the landlord billed $88,500, the identified adjustments should explain the full $6,500 difference. Totals that cannot be traced are themselves a finding that requires clarification.

Step 7: Dispute in writing

Send the objection within the lease’s window and use the required notice method. Identify each issue, amount, calculation, and supporting clause. Separate confirmed arithmetic differences from questions that require more records.

Keep proof of delivery and a complete copy of the submission. A clear schedule makes the discussion easier for both sides because each item can be answered directly.

Where software fits

Much of this work is mechanical: reconciling every statement line against definitions, recalculating shares, applying caps, and tying findings to clauses. Tools can now perform that comparison in minutes, but the output still needs transparent inputs and exact support.

Leaseful reconciles CAM lines against the tenant’s governing lease terms and attaches the supporting clause to each finding. Whether the review is manual or software-assisted, the standard is the same: every dollar should trace from the statement through the lease to the final calculation.