CAM reconciliation is the annual process of comparing what tenants paid in monthly CAM estimates against the actual common area maintenance expenses for the year. If tenants overpaid, they receive a credit or refund. If they underpaid, you bill them for the difference. The concept is straightforward. The execution is where most property managers get tripped up.

The core formula is pro-rata share. Each tenant’s share equals their leasable square footage divided by the total leasable square footage of the property. A tenant occupying 5,000 square feet in a 50,000 square foot building has a 10% share of reconcilable CAM expenses. Multiply that percentage by total actual CAM for the year and you get what the tenant should have paid. Subtract what they actually paid in monthly estimates and you have the reconciliation amount, either a bill or a credit.

Expense categorization is where the work lives. Most leases define exactly what qualifies as CAM, and lease terms vary by tenant. Typical categories include landscaping, parking lot maintenance, exterior lighting, security, property management fees, common area utilities, trash removal, and general repairs. Capital improvements usually don’t pass through unless the lease explicitly allows them. Some leases cap administrative fees at a percentage of total CAM. Others exclude specific items like roof replacement or structural repairs. You have to read each lease, not just apply a generic template.

Base year provisions, expense stops, gross-up calculations, and annual caps add further complexity. A tenant on a base year lease only pays for increases over the base year amount, not the full expense. Gross-up calculations come into play when the building isn’t fully occupied, because fixed costs need to be normalized to reflect what they would be at full occupancy. Annual caps limit how much certain categories can increase year over year. Missing any of these produces either an overbilling that gets disputed or an underbilling that costs the owner money.

Timing is driven by the leases themselves. Most commercial leases require CAM reconciliations be delivered to tenants within 30 to 90 days of fiscal year-end, and some go out to 120 days. Missing the deadline can limit the owner’s ability to collect underpayments, and some leases void the billing entirely if it isn’t delivered on time. The year-end close process needs to be built around those dates.

Documentation has to support every number. Larger tenants with audit rights will request backup for CAM expenses, and trying to reconstruct clean records at year-end from messy books usually leads to disputes. Clean expense categorization throughout the year, invoices organized by CAM pool, and a clear audit trail make the reconciliation defensible.

The systems matter too. Yardi and similar property management platforms handle CAM reconciliations well when configured correctly. The chart of accounts needs to separate recoverable from non-recoverable expenses, expense categories need to map to lease-defined CAM pools, and tenant square footage and share percentages need to be set up accurately. Without that setup you end up reconciling in spreadsheets, which is fine for a small portfolio but breaks down at scale.

Dennis spent nearly a decade at an S&P 500 REIT and currently handles property management accounting at a Los Angeles development firm, including CAM reconciliations, lease-level billing, and operating expense recoveries in Yardi. If you manage commercial property in the San Gabriel Valley and need help setting up reconciliable books or running year-end CAM, our bookkeeping services in Pasadena are built around that exact work.