CAM stands for common area maintenance. CAM reconciliation is the annual process of comparing the estimated operating expenses that tenants paid throughout the year against the actual costs the property incurred. At year end, you true up those estimates to the real numbers and bill or credit each tenant for the difference.

Most commercial leases require tenants to pay their share of building operating costs. But those costs are not known until the year is over. So tenants pay estimates monthly, and you reconcile once you have final numbers. The expenses included typically cover property taxes, building insurance, common area utilities, landscaping, parking lot maintenance, security, janitorial for common spaces, and maintenance for shared building systems.

Here is how it works in practice. At the start of each lease year, you estimate what operating expenses will be for the building. Tenants pay their pro-rata share of that estimate each month, usually based on their square footage as a percentage of the building’s rentable area. Once the year closes and you have actual costs, you compare them to what tenants paid. If actual costs came in higher than the estimates, tenants owe the difference. If costs were lower, tenants receive a credit.

You need CAM reconciliation if you own commercial real estate leased under triple-net or modified gross structures. This includes most retail centers, office buildings, and industrial properties. If your leases pass operating expenses through to tenants with an annual true-up provision, the reconciliation is required.

Accuracy matters because CAM reconciliation directly affects what you bill tenants. Overstating expenses exposes you to tenant disputes and potential lease violations. Understating means you leave money on the table. Either way, errors create friction with tenants and throw off your cash flow projections.

Getting it right requires tracking operating expenses at the property level throughout the year, knowing what each lease allows you to include, and producing clear documentation that tenants can review. Some leases cap annual increases or exclude certain cost categories, so you need to reconcile to the specific terms in each agreement. A fractional CFO for real estate who understands lease structures and property-level accounting can handle this properly and keep your tenant relationships clean as your portfolio grows.