How to audit common area maintenance charges on a commercial lease

To audit common area maintenance charges, reconcile the landlord's reconciliation statement against your specific lease, one line at a time. Confirm your pro-rata share is still correct, strip out any charge the lease excludes, apply every cap the lease sets, and verify the gross-up and base-year calculations. CAM is where the biggest billing leaks happen, because the pool is large, the categories are vague, and few tenants check the statement against the actual lease language before paying. The audit is the check.

CAM, or common area maintenance, is the tenant’s share of the cost to operate and maintain shared areas of a property: parking lots, landscaping, lighting, security, and similar. Under a net lease the landlord estimates these costs, bills them monthly, then reconciles once a year against actual spend and sends a true-up. The reconciliation is where errors and overcharges surface, and where your lease, not the landlord’s ledger, is the authority.

The CAM audit checklist#

Work these steps in order against the year-end statement and your lease.

1. 01Pull the lease and the reconciliation. Get the executed lease with all amendments, the year-end CAM reconciliation, and the supporting detail or general ledger if the lease grants access.
2. 02Confirm the audit right and the deadline. Find the audit clause, diary the dispute deadline first, because missing it can forfeit the recovery.
3. 03Verify your pro-rata share. Recalculate your share as your rentable square footage over the correct denominator; a share that never updated after a remeasurement is a quiet overcharge.
4. 04Remove excluded items. Strike anything the lease excludes: often capital expenditures, structural and roof replacement, financing costs, leasing commissions, and costs reimbursed by insurance or other tenants.
5. 05Separate capital from operating. Confirm capital projects are not billed as operating expense; a roof replacement categorized as a repair is the most frequent expensive misclassification.
6. 06Apply every cap. Check contractual caps on controllable expenses and on management or administrative fees, and confirm whether caps are cumulative or annual and compounding.
7. 07Check the gross-up. In a building below full occupancy, gross-up should apply only to variable expenses and must not inflate your share above full-occupancy cost.
8. 08Test the base year on office leases. Confirm base-year expenses were calculated on the same basis as the comparison year, with no items added later.
9. 09Check anchor and vacancy allocation. Confirm anchor tenants and vacant space carry their proper share, so their costs are not shifted onto you.
10. 10Reconcile estimates to actuals. Tie the monthly estimates you paid to the reconciled actuals and confirm the true-up direction and amount.
11. 11Document and dispute. Write up each finding with the lease clause attached and send the dispute inside the audit window.

Where CAM overcharges hide#

Five patterns account for most of what an audit recovers:

• Capital expenditures billed into the operating CAM pool, such as a roof or parking-lot replacement treated as a repair.
• Management or administrative fees charged above the contractual cap, or applied to excluded categories like taxes and insurance.
• An outdated pro-rata share after a remeasurement or a change in the property's gross leasable area.
• Excluded items left in the pool, from landlord financing costs to expenses already reimbursed by insurance.
• Anchor or vacancy costs misallocated to inline tenants rather than absorbed where the lease requires.

Each of these is a lease-language question, which is why the statement alone never tells you whether a charge is valid.

Why the deadline matters#

Most leases allow a tenant to audit CAM only within a limited window, commonly one to three years, and sometimes require written notice within a set number of days after the reconciliation is issued. Miss it and you can lose the right to recover for that year, no matter how clear the overcharge. Treat the audit window as a critical date, tracked like a renewal or option deadline, not a task you get to when the quarter is quiet.

Doing this across a large portfolio#

For one location, this is an afternoon with the lease and a spreadsheet. Across hundreds of locations, every reconciliation arrives on its own schedule, each against a different lease with different caps and exclusions, and the audit windows expire quietly. That is why most portfolio-level CAM overcharges go uncaught: not because they are hard to find, but because no one has time to check every statement against every lease before the clock runs out.

This is the work our Lease Intelligence agent is built to do. It checks each CAM reconciliation against the specific lease, flags disallowed charges, cap breaches, and pro-rata errors with the clause attached, and prepares the recovery letter the moment one shows up, so the overcharges get caught and the deadlines do not slip. For the broader operating picture, see portfolio optimization.