CAM reconciliation: the lease terms and invoices each statement depends on

CAM reconciliation settles a tenant's common area maintenance (CAM) charges at the end of each year. The landlord compares the estimates the tenant paid during the year with the tenant's share of the actual costs. The tenant then pays the shortfall or gets a credit. The lease sets the rules for each number, so one misread lease term makes the statement wrong.

Property accountants and lease administrators on the landlord side prepare these statements, one building at a time. Lease administrators at multi-site tenants check the statements they receive, and there's a section for them near the end.

What is CAM reconciliation?#

CAM is the cost of running the shared parts of a commercial property. It covers things like the lobby, the parking lot, landscaping, snow removal and security. Each tenant pays a monthly estimate during the year, based on the landlord's budget. After the year closes, the landlord works out what each tenant owes under its lease. It then sends a statement with the balance due or the credit.

What the tenant owes depends on the kind of lease. In a triple-net (NNN) lease, the tenant pays its share of all the property's taxes, insurance and CAM. In a base-year office lease, the tenant pays its share of costs only above their level in a base year. In office leases, the same settlement is often called an operating expense reconciliation. The steps are the same for both kinds of lease.

The lease usually sets the timetable too. It says when the statement is due and when the tenant pays or gets its credit. It also says how long the tenant has to question the numbers.

The lease terms that set each tenant's share#

A few lease terms decide the math. They can sit in different parts of the lease, and a later amendment can change any of them. The lease below is the one on our lease abstraction page. Its Parties tab holds the tenant's share, and its Expenses tab holds the base year and the cap.

These are the terms to find in every lease and amendment before any math starts.

Real leases spread these terms out. One example is the 2022 Century Square office lease, which the Texas A&M University System posts online. The System's Board of Regents is the tenant. The share formula sits in section 4.4, near the front. The estimates, the 120-day statement deadline and a gross-up to 100% occupancy are in section 5.3. A 3% limit on the management fee is item 17 of Exhibit G. The 22 numbered exclusions fill Exhibit I, the last three pages of an 81-page file.

The same lease has the landlord's architect remeasure the suite and the building within 30 days after the commencement date. The parties then sign an amendment, and the share changes if the area does. So the 14,596 square feet printed on page 1 may not be the area that applies. The share can also change each year, because section 4.4 divides by the building's office space on January 1. Build the statement from the lease and every amendment, read together. That's what a lease abstract is for.

A CAM reconciliation example#

Here is one tenant's 2025 statement, worked from the lease in the figure. Cobalt Ridge leases Suite 300 at Lakeview Commerce Center, 6,000 of the building's 48,000 rentable square feet. Its lease sets a 12.50% share, a 2024 base year for operating expenses and taxes, and a 5% yearly cap on controllable costs. Cobalt Ridge paid $400 a month in estimates during 2025, or $4,800 in all.

The ledger shows $528,000 of operating expenses for 2025. Of that, $324,000 is controllable costs, the ones the landlord can manage, such as cleaning and repairs. The other $204,000 is utilities and insurance. Here they count as uncontrollable, so the 5% cap doesn't apply to them.

The utilities include $6,000 of after-hours air conditioning that the landlord billed straight to Keller & Voss, the tenant in Suite 200. The landlord recovers that charge from Keller & Voss, so the accountant removes the $6,000 from the shared pool. The Century Square lease excludes the same kind of cost, in item 6 of Exhibit I.

The cap removed $9,000. Controllable costs rose 8%, from $300,000 in 2024 to $324,000, and the lease allows 5%, or $315,000. Last year's file supplies that $300,000, so it matters as much as this year's ledger.

The rent roll adds one more fact. Suite 350, 4,500 square feet, stood empty all year. Cobalt Ridge's lease fixes its share at 12.50% of the whole building, so the landlord pays the empty suite's part of the increase itself. If a lease has a gross-up clause, the gross-up is one more step here. The clause also says whether the gross-up comes before or after the cap.

Each mistake below adds at least $580 to the $825 balance due.

Our take. None of these three mistakes can be seen in one document alone. The air conditioning charge looks normal in the ledger until someone compares it with the invoice to Keller & Voss. The occupied-space share looks fine until someone reads the lease next to the rent roll. So we'd judge any tool for this work by the checks it runs between documents, not by how well it reads a single lease.

The CAM reconciliation process#

For a whole building, the work runs in this order.

1. Close the year's booksPost the last invoices and accruals for the property, so the general ledger shows the year's actual costs.
2. Build the cost poolsMap each expense account to a pool, such as CAM, taxes or insurance. Set aside costs no tenant pays, and keep the invoice behind every line.
3. Take the terms from each leaseRead the share, denominator, base year, caps, exclusions, gross-up and admin fee. For each term, use the latest amendment that changed it.
4. Work out each tenant's shareRemove that lease's exclusions, then apply the gross-up and cap in the order the lease sets. Subtract any base year or expense stop, then apply the share.
5. Compare with the estimates billedThe difference is the balance due or the credit. Prorate tenants who moved in, moved out or expanded during the year.
6. Send the statementsSend each one before the lease deadline, with its expense schedule, and reset next year's monthly estimates.

Tenants can ask for backup, meaning the documents that prove each cost. The invoices kept in step 2 are that backup. In California, the law now requires it for some small tenants.

Civil Code section 1950.9 took effect in January 2025. It covers microenterprises, restaurants with fewer than 10 employees and nonprofits with fewer than 20 employees. State law defines a microenterprise as a business with five or fewer employees, including the owner, that generally lacks access to loans or other capital. A tenant qualifies by giving the landlord written notice of its status and its own statement of its employee count. Under a lease, it gives both at or before signing and every year after. A month-to-month tenant qualifies if it gave them in the last 12 months.

For a qualifying tenant, the landlord can charge only that tenant's proportionate share of the building's operating costs, by square footage or another documented method. Costs that a tenant, an insurer or another third party has paid back to the landlord, like the Keller & Voss charge, don't count. On written request, the landlord must send dated, itemized backup, such as invoices or receipts, within 30 days. The backup must show how the costs were allocated among tenants, with the landlord's signed and dated statement that they're correct. The landlord can't charge the costs until it has provided that backup.

The rule covers leases signed, started or renewed from 2025, month-to-month and shorter tenancies, and older leases that say nothing about building operating costs.

Checks to run before statements go out#

Run these on the whole building, not one tenant at a time.

• Square footageEach tenant's area and the building total match the lease, its latest amendment and the rent roll.
• Shares add upWhere the denominator is the whole building, tenant shares plus vacant suites come to 100%. At Lakeview, five leases hold 90.625% and Suite 350 holds the other 9.375%.
• Exclusions, lease by leaseEvery invoice in the pool is checked against each tenant's own exclusion list. One lease can exclude a cost that another allows.
• Bill-backsCosts billed straight to one tenant, like the after-hours air conditioning at Lakeview, are out of the shared pool.
• Caps and base yearThe cap starts from the year the lease sets, such as Lakeview's 2024 controllable costs in last year's file. It comes before or after gross-up, as the lease says. The base-year figures match last year's statement.
• Estimates billedThe estimates on each statement match what the billing system charged the tenant for the year.
• Partial yearsTenants who moved in, moved out or expanded mid-year are prorated for the time they held the space.

Our guide to rent roll automation covers what a rent roll holds and the checks lenders run on one.

If you check CAM statements for a tenant#

Lease administrators at retail chains, restaurant groups and other multi-site tenants work with the same documents from the other side. A chain with 200 locations can receive 200 statements a year, each built on a different lease. These lease administrators ask the questions in the checklist above, starting with the share and the area it's divided by.

Check each statement against your own lease abstract before you check the arithmetic. A correct sum on the wrong share is still wrong. Ask for the invoices behind any line that rose sharply from last year. On the day the statement arrives, write down the lease's deadline for questions or an audit.

Where Docsumo fits, and where it stops#

Docsumo reads the documents a reconciliation starts from. It isn't limited to pre-built models, the ones trained in advance for common document types. So it reads commercial leases and their amendments in any landlord's form, including the CAM terms. It reads the expense backup too, from vendor invoices to utility bills and property tax bills. You can send invoices to Docsumo by email, by upload or through the API. The Data Table collects a year of invoices into one table that you can review and export to CSV or Google Sheets. When Docsumo is unsure of a value, it sends the value to your team. Clicking a value highlights the line in the document it came from.

On the Enterprise plan, cross-document validation checks the documents against each other. It can check each invoice against a lease's exclusions, and each tenant's area and share against the rent roll.

You can also set up a step in the workflow that runs your own Python code to work out each tenant's share. The reconciliation itself still stays in your property management system or spreadsheet, and so do tenant billing and the ledger. The data goes to your system through the API and webhooks, or out as an Excel or CSV export. Docsumo supplies the software, not a team that prepares the statements for you. It also reads other property documents the same way, such as T-12s and rent rolls. Our page on intelligent document processing for real estate covers the rest.

Before next year's statements go out#

Start with the leases that changed this year, such as renewals, expansions and remeasured suites. Their statements are the ones that can carry an old share or an old base year. Then match this year's invoices against each lease's exclusions while the backup is still easy to find.

Book a demo with one of your leases and a year of invoices, or start a free trial.

Frequently asked questions#