The bill comes after the billing period. It is not monthly rent. It is a CAM bill. It shows a balance after prior pay. The bookkeeper needs two answers. Where does it go? Does the lease back it? See how CAM reconciliation works for bookkeepers.
This article covers what the CAM true-up is, how it is calculated, why it lands when it does, and what the accounting team needs to know before coding the payment.
CAM (Common Area Maintenance): CAM stands for Common Area Maintenance. In a commercial lease, CAM charges are the tenant's share of the operating expenses the landlord incurs to run the building: cleaning, landscaping, security, insurance, property taxes, management fees, utilities for shared spaces, and similar costs. CAM is billed in addition to base rent and is one of the defining features of a NNN (triple-net) or modified gross lease.
What the Annual Reconciliation Actually Is
The lease may set monthly CAM amounts. It may say how they can change. Read the lease for the right method.
The problem with estimates is that they are never exactly right. By the end of the year, the landlord has collected a fixed amount from the tenant and has spent a different amount running the building. The annual reconciliation, also called the true-up, settles the difference.
The bill lists the amount due. It may give a pay date.
Why It Arrives During Close Week
The lease may set a due date for the bill. Read it. Do not use a common date range as a rule.
A firm may get more than one true-up at once. Add a task for each bill. Do not assume each lease has the same date.
The practical effect: the CAM true-up is a recurring, predictable Q1 event that deserves its own close task, not treatment as a surprise exception.
What the Reconciliation Statement Contains
The format varies by landlord, but a standard reconciliation statement includes:
The total cost pool. This lists costs the landlord plans to share. The bill may not list each cost. Read the lease before you ask for more detail.
The tenant pro-rata share. This is the percentage used to allocate the pool to the specific tenant. It is derived from the tenant square footage divided by some denominator, which the lease specifies. The denominator matters: some leases use total building square footage, others use occupied square footage, and some use total leasable square footage. Each produces a different pro-rata share.
The CAM paid each month. This is the CAM the tenant paid that year. It shows as a credit against the tenant's share.
The balance due or credit. The difference between the allocated share and the estimated payments. If positive, the tenant owes the balance. If negative, the landlord applies it as a credit toward future monthly estimates or issues a refund, depending on the lease terms.
The Accounting Question It Creates
When the reconciliation arrives, the bookkeeper faces a question that goes beyond where to code it: is this a current-year expense or a catch-up for the prior year.
The expense belongs to the period when the building operated. A reconciliation delivered in March 2026 for calendar year 2025 is a 2025 expense. If the practice has been on accrual accounting and the bookkeeper has been tracking estimated versus actual CAM throughout 2025, there may already be an accrual in the books for the expected shortfall. In that case, the true-up payment settles the accrual.
If no accrual exists, use the firm's rules. Size and date may change the entry. Ask the controller how to post it.
The key point is that the CAM true-up and the monthly CAM estimates are two different transactions that need to be tracked separately in the books. Booking them both to a single "rent" account hides the distinction and makes year-over-year comparison impossible.
What the Monthly Estimates Represent
Monthly CAM estimates are the landlord's best guess at what the tenant's share of operating costs will be for the year. They are collected in advance, like rent, and they cover costs that will be incurred throughout the year.
For the bookkeeper, the estimate adjustment creates a new budget line item. The client needs to know that their occupancy cost has increased, not just that their rent has changed.
Before You Code the Payment
Four things to check before coding a CAM true-up payment:
Does the pro-rata share match the lease? Pull the lease abstract and confirm the percentage on the reconciliation matches what the lease specifies, including the denominator used. A difference of half a percentage point on a $890,000 expense pool is $4,450.
Does the lease exclude any costs? Check the limits in the signed lease. If the bill lacks a line-by-line list, ask for one before paying.
Is there a CAM cap? A lease may cap some cost hikes. If a cost jumps, test it against the lease.
What is the audit due date? Read the lease and log the date. Ask counsel what happens after it.
The accounting is separate from the accuracy question. Coding the payment correctly is step one. Confirming the underlying charge is correct is step two. For any true-up above a few thousand dollars, both steps matter.
"I built CAMAudit to help partners compare the lease with the reconciliation before they advise a client." - Angel Campa, Founder of CAMAudit
The Pattern Across Multiple Clients
For CAS firms and outsourced controllers managing more than one commercial tenant, the CAM true-up is a portfolio event. A 3-location retailer with stores in different buildings may receive three separate reconciliations in February and March, each from a different property manager, each using a different format, each requiring the same set of checks.
Building a standard intake checklist for CAM reconciliation statements, the same way firms use standard intake for 1099s or depreciation schedules, turns a recurring exception into a routine procedure. The checklist logs the statement date (starts the audit clock), the balance due amount, the pro-rata share, and whether backup was included or needs to be requested.
That procedure does not require expertise in commercial real estate. It requires the same attention to source-document accuracy that bookkeepers apply to every other expense category.