Real Estate Tax Calc
Worked example: strip mall CAM reconciliation from start to finish
Start with the numbers before the explanation. A landlord owns a 10,000-square-foot strip mall with three tenants:
| Tenant | Leased sq ft | Pro-rata share | Monthly CAM estimate | Annual CAM estimate |
|---|---|---|---|---|
| Tenant A (salon) | 4,000 | 40% | $960 | $11,520 |
| Tenant B (insurance office) | 3,500 | 35% | $840 | $10,080 |
| Tenant C (florist) | 2,500 | 25% | $600 | $7,200 |
| Total | 10,000 | 100% | $2,400 | $28,800 |
The landlord budgeted $28,800 in CAM for 2026. Actual CAM costs incurred during 2026:
- Parking lot sweeping and snow removal: $8,400
- Landscaping and irrigation: $7,200
- Exterior lighting maintenance: $3,600
- Common-area cleaning and trash removal: $6,000
- Property management fee (8% of gross CAM): $2,304
- Insurance for common areas: $6,000
- Total actual CAM costs: $33,504
CAM shortfall: $33,504 − $28,800 = $4,704. Each tenant owes a reconciliation payment based on their pro-rata share:
| Tenant | Share | Annual estimate paid | Actual allocation | Reconciliation due |
|---|---|---|---|---|
| Tenant A | 40% | $11,520 | $13,402 | $1,882 |
| Tenant B | 35% | $10,080 | $11,726 | $1,646 |
| Tenant C | 25% | $7,200 | $8,376 | $1,176 |
The landlord bills these reconciliation amounts to tenants in January or February 2027. Receipt of the $4,704 total is additional rental income in 2027 (cash basis) or in 2026 (accrual basis, once the obligation is fixed and the statement is sent). The landlord deducted $33,504 in actual CAM costs during 2026. Net effect on taxable income: $33,504 income − $33,504 expenses = zero — a wash, but both amounts flow through the return.
What is CAM reconciliation?
Common Area Maintenance (CAM) refers to the shared operating costs of a commercial property's common areas — parking lots, hallways, lobbies, landscaping, exterior lighting, roofs over common areas, and similar features. Under most commercial leases (net leases, modified gross leases, and many full-service gross leases with expense stops), tenants pay a portion of these costs in addition to base rent.
Because landlords cannot know actual CAM costs for the year in advance, most leases require tenants to pay a monthly CAM estimate — a budgeted amount based on the prior year's costs plus an escalation factor. At the end of the lease year, the landlord computes actual CAM costs, compares them to estimates collected, and issues a CAM reconciliation statement. If actual costs exceeded estimates, tenants owe the difference. If estimates exceeded actuals, the landlord owes a refund or credit.
CAM reconciliation is a standard feature of triple net (NNN), double net (NN), and many modified gross commercial leases. The specific costs included in CAM — and any excluded items, caps, or audit rights — are defined in the lease itself. Tax treatment follows the lease mechanics and the taxpayer's accounting method.
Landlord's tax treatment: income and expense reporting
For a commercial landlord, all amounts received from tenants — base rent, CAM estimates, and CAM reconciliation payments — constitute gross rental income under IRC §61. The landlord reports this income on Schedule E (individuals) or the entity's business return (Form 1065, 1120-S, etc.).
Monthly CAM estimates are rental income when received (cash basis) or when earned (accrual basis). They do not receive special treatment as "reimbursements" — they are ordinary income the moment they enter the landlord's hands.
Year-end reconciliation payments from tenants are additional rental income, reported on the same schedule. The timing depends on the landlord's accounting method:
- Cash basis: Report the reconciliation payment as income in the tax year it is actually received. If tenants pay the January 2027 reconciliation bill in February 2027, it is 2027 income.
- Accrual basis: Report the income in the year the right to receive it becomes fixed and determinable — typically when the landlord delivers the CAM reconciliation statement to tenants (which may be late 2026 or early 2027 depending on the lease timeline). Many landlords use accrual accounting for commercial properties.
Actual CAM costs are deductible operating expenses in the year incurred, regardless of when tenants are billed for their share. Landscaping, snow removal, common-area cleaning, exterior lighting, and property management fees are typical operating-expense CAM items — deductible under §162 in the year the service is performed or the obligation accrues.
Capital CAM items — paving a new parking lot, replacing a roof, adding new exterior lighting fixtures — must be capitalized and depreciated even if the lease allows them to be passed through to tenants. The landlord capitalizes the cost and recovers it through depreciation; the fact that tenants contractually share the cost through CAM charges does not convert a capital expenditure into a currently deductible expense. The landlord's CAM income from billing tenants for a capitalized item and the ongoing depreciation deduction create a timing mismatch that is worth flagging at year-end.
Tenant's tax treatment: deducting CAM charges
Commercial tenants deduct CAM charges — both monthly estimates and reconciliation payments — as ordinary and necessary business expenses under IRC §162. The deduction appears on Schedule C (sole proprietors), Form 1065 (partnerships), Form 1120-S (S corporations), or Form 1120 (C corporations) as rent expense or occupancy cost.
The accrual-method tenant recognizes the deduction when the CAM obligation becomes fixed and determinable. For monthly estimates, this is each month as the obligation accrues. For the annual reconciliation, the deduction is typically available in the year the landlord delivers the final CAM statement — even if payment is not due until early in the following year.
When a landlord issues a refund or credit for CAM overpayment, the tenant must reduce its deduction for the year the credit applies. The refund is not income — it is a reduction in occupancy expense. If the refund relates to a prior-year deduction, the tenant may need to reduce the current-year deduction (and potentially file an amended return for the prior year if the amount is material).
CAM caps, exclusions, and gross-up clauses
Commercial leases frequently modify the basic CAM pass-through in ways that affect both tax amounts and dispute risk:
CAM caps limit how much CAM charges can increase from one year to the next — commonly 5% or 8% cumulative increases per year. If actual costs rise faster, the landlord absorbs the excess. For tax purposes, the cap determines what the tenant is obligated to pay; the landlord deducts actual costs regardless of the cap. The cap affects revenue, not expense treatment.
CAM exclusions are items the landlord agrees to keep out of the CAM pool — capital expenditures, management fees above a specified percentage, depreciation of building improvements, and sometimes taxes and insurance (which may be billed separately as the other "nets" in NNN and NN leases). Exclusions matter for tax because landlords cannot bill tenants for them in CAM, so the landlord bears those costs alone and deducts them separately.
Gross-up clauses require the landlord to adjust variable CAM expenses as if the building were fully occupied, even when vacancy exists. This prevents partially-occupied buildings from producing below-budget CAM estimates that then spike when occupancy fills — keeping the building's CAM burden from disproportionately falling on the occupied tenants. For tax purposes, the gross-up affects the billing amount (and thus the income the landlord reports); it does not create phantom income, since the landlord reports only what is actually billed and collected.
CAM audit rights and dispute resolution
Most commercial leases give tenants the right to audit the landlord's CAM calculations — typically within 60 to 180 days of receiving the annual statement. When a tenant exercises audit rights and discovers overcharges, the resulting credit or refund has tax consequences for both parties:
The landlord who issued an overcharge must refund it, which reduces the year's rental income (or creates a deductible expense adjustment) in the year the refund is paid. If the overcharge occurred in a prior year, the landlord may need to amend that return or account for the correction in the current year depending on the amount and materiality.
The tenant who receives a CAM audit refund has overstated its occupancy expense in a prior year. The correct treatment is to reduce the current-year deduction by the refund amount (not to report it as income). If the amount is large enough to materially distort a prior year's return, filing an amended return is appropriate.
From a practical standpoint, most CAM audits settle through credit adjustments rather than cash refunds — the tenant's next year's monthly CAM estimate is reduced by the overcharge. The tax treatment follows the same logic: the reduction is a decrease in occupancy expense for the year the credit applies.
CAM reconciliation in NNN vs. modified gross leases
How CAM reconciliation works depends on the lease structure:
Triple net (NNN) leases pass property taxes, insurance, and maintenance entirely to tenants. In a true NNN structure, tenants may pay CAM costs directly to vendors (landscapers, snow removal contractors) rather than reimbursing the landlord. When tenants pay vendors directly, the landlord never touches the money and reports only base rent as income. When tenants reimburse the landlord who then pays vendors, the landlord grosses up: CAM reimbursements are income, and CAM costs paid to vendors are expenses. Both structures reach the same taxable income, but the gross-up method reports larger gross income figures on the return.
Modified gross leases typically include some operating expenses in the base rent up to a fixed "expense stop," with CAM charges covering only the excess above that stop. The reconciliation process still applies but covers only the costs above the stop. The landlord deducts all actual costs (including those below the stop that tenants don't pay for) and reports tenant reimbursements as income. The stop level creates a natural floor below which the landlord bears the cost with no corresponding income.
Frequently asked questions
How does a landlord report CAM reconciliation income?
CAM reconciliation receipts are rental income, reported on Schedule E or the applicable business return. Under the accrual method, income is recorded when the reconciliation is billed to tenants — typically within the first 90 days after year-end. Under the cash method, income is reported when payment is received.
How does a tenant deduct CAM charges?
CAM charges — both monthly estimates and reconciliation payments — are ordinary and necessary business expenses deductible under IRC §162. The accrual-method tenant deducts the reconciliation adjustment when the obligation becomes fixed and determinable, which is typically when the landlord delivers the annual CAM statement.
Are CAM charges taxable income to the landlord?
Yes. All amounts received from tenants, including CAM reimbursements, are gross rental income. The landlord then deducts the actual CAM costs as operating expenses. The net is typically a wash, but both sides must flow through the return separately — reporting only the net, or omitting either side, is incorrect.
What happens when estimated CAM payments exceed actual costs?
The landlord owes a refund or credit to tenants. The overpayment is not taxable income to the tenant; it reduces the tenant's occupancy expense deduction for the year the credit is issued. The landlord reduces income (or records a deductible expense adjustment) for the same year.
Can a landlord deduct capital CAM items immediately?
No. Capital expenditures to common areas — new parking lot, roof replacement, structural lighting upgrades — must be capitalized and depreciated under the tangible property regulations, even if the lease allows the landlord to pass the cost through to tenants in CAM. Only ordinary operating expenses (cleaning, landscaping, minor repairs) are currently deductible CAM costs.
Does the gross-up provision affect the landlord's taxable income?
A CAM gross-up adjusts the billing to tenants as if the building were fully occupied. For tax purposes, the landlord reports the actual amounts billed and collected from tenants as income, and deducts actual costs incurred. The gross-up does not create phantom income — it only determines the invoiced amounts, which are then reported as income when received or accrued.
Educational information and estimates only. Not tax advice. Tax rules change and vary by situation; consult a qualified tax professional before acting.