The invoice arrives in February. It is not the regular monthly rent. It is a CAM reconciliation statement, and it says the tenant owes $3,400 on top of what they have already paid. For the bookkeeper processing it, there are immediately two problems: first, where does this go in the books, and second, is this number even right. For more context, 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
Under most commercial leases, the landlord collects CAM in the form of monthly estimates. The lease will specify an initial estimate amount, and each January (or at another lease anniversary) the landlord is permitted to reset the monthly estimate based on projected costs for the coming year.
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.
Here is the basic structure. A dental practice on a NNN lease pays $1,200 per month in estimated CAM. Over twelve months that is $14,400. The landlord runs the numbers for the year and determines that the total building operating costs were $890,000. The building is 120,000 rentable square feet, and the dental practice occupies 2,400 square feet. The pro-rata share is 2.0 percent. Two percent of $890,000 is $17,800. The tenant has already paid $14,400. The balance due is $3,400.
That $3,400 shows up on the reconciliation statement as a charge due by a specific date, often 30 days from delivery of the statement.
Why It Arrives During Close Week
The timing is not random. Most commercial leases set a contractual deadline for the landlord to deliver the annual reconciliation, typically 90 to 120 days after the end of the calendar year. That window runs from late March to late April. Some leases use a 180-day deadline, which stretches to June.
Landlords who manage large portfolios tend to batch the work. A property management company running 15 buildings does not prepare 15 reconciliations on 15 different schedules. They close out the books for all buildings in January and February and then release the statements to all tenants at once in March. For a CAS firm or outsourced controller with multiple commercial tenant clients, this means receiving multiple CAM true-up statements from different landlords in the same two-week window, often the same two-week window that already contains Q1 close work.
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 expense pool. This is the aggregate of all operating costs the landlord is allocating to tenants for the year. Line-item detail may or may not be included in the statement. If it is not included, the tenant has the right under most leases to request it.
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 estimated payments already made. This is the sum of the monthly CAM estimates the tenant paid during the year. It appears as a credit against the total allocated 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, the payment hits the books in March 2026 as a prior-period adjustment or a current-period expense depending on materiality and the firm's accounting policies. For small businesses, this is often treated as a current-year expense in the month of payment. For clients with more rigorous reporting, the controller may need to restate the prior-year period.
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.
Most leases allow the landlord to adjust the monthly estimate each year. An adjustment notice from the landlord in December or January is a signal that the true-up from the prior year showed a shortfall, and the landlord is resetting the estimate to reflect actual costs. A client whose monthly CAM estimate jumps from $1,200 to $1,650 in January is seeing the downstream effect of the prior year's reconciliation.
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.
Are there any excluded categories in the lease? Commercial leases commonly exclude capital expenditures, management fees above a stated cap, and certain categories like executive salaries or costs related to other tenants. If the reconciliation does not include a line-item breakdown, request one before paying.
Is there a CAM cap provision? Some leases limit how much controllable CAM expenses can increase year over year, typically 3 to 5 percent annually. If the reconciliation shows a significant jump, the cap may reduce what the tenant owes.
What is the audit right deadline? Most leases give tenants 12 to 36 months from the date the reconciliation is delivered to audit the landlord's records. Once that window closes, the right to dispute is typically waived. Log the deadline when the statement arrives.
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 because the accounting team almost always codes the payment before anyone asks whether the number is right. By the time a client asks a question, the audit window is often already half gone." — 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.