Property taxes are often the single largest line item in a commercial CAM statement — and they are also one of the most frequently misallocated. I built CAMAudit partly because I kept seeing the same tax-related errors come up when testing reconciliation samples through the system. The math looks official. The numbers are large. Most tenants just pay.
They shouldn't.
How Property Taxes Work in Commercial Leases
In a triple-net lease, the tenant pays their proportionate share of the building's property taxes in addition to base rent. The landlord receives the tax bill, pays it, and then passes that cost through to tenants as part of the annual CAM reconciliation.
The mechanism seems straightforward: the county assesses the property, issues a bill, the landlord pays it, tenants reimburse their share. But several things can go wrong between the county's bill and what lands on your CAM statement — and none of them are accidents.
40% of CAM reconciliations contain material errors, with tax line items among the most common categories flagged (Tango Analytics / PredictAP, 2023)
Common Overallocation Patterns
Mixed-Use Buildings: Only Commercial Tenants Paying the Full Bill
This is the scenario that comes up most in our detection results. A landlord owns a building with both commercial and residential floors. The property tax bill covers the entire structure. But when allocating costs through CAM, only the commercial tenants receive the charge.
The residential component is excluded from the denominator. The pro-rata share calculation is run only against commercial square footage. The result: commercial tenants are covering a larger portion of the tax bill than their actual share of the property justifies.
Your lease should specify what the denominator is. If it says "total rentable area of the building" or "total leasable area," that includes residential space. If the landlord is running the math on commercial-only square footage, you are subsidizing the residential tenants.
Special Assessments Your Lease Excludes
Many leases explicitly exclude certain pass-throughs from the definition of real estate tax. Special assessments are a common exclusion — things like local improvement district charges, sidewalk repair levies, or infrastructure bond repayments imposed by a municipality.
These assessments appear on the same property tax bill, right alongside the ordinary ad valorem tax. Landlords sometimes bundle them all into a single "Real Estate Taxes" line on the CAM statement without separating assessable items from excluded assessments.
If your lease says special assessments are excluded, that line should be zero. Check what your landlord actually itemized.
Tax Appeals: Where Did the Credit Go?
This one gets missed constantly. When property taxes are assessed higher than the market value warrants, landlords have the right to appeal. Appeals take time — sometimes 18 to 24 months. During that window, the landlord passes through the full assessed amount to tenants.
When the appeal settles and the landlord receives a refund from the county, tenants who paid the inflated amount during the appeal period are entitled to a credit on their next reconciliation.
Many landlords handle this correctly. Some do not. The refund quietly disappears into the landlord's bank account while tenants received no reconciliation adjustment.
Ask your landlord directly: did you file any tax appeals in the last three years? If an appeal was filed and settled, where is the corresponding credit on my reconciliation?
The California Proposition 13 Problem
California deserves its own section because of Proposition 13, which caps annual property tax increases at 2% per year — but allows the county to reassess the property to current market value upon a sale.
When a landlord sells a California commercial property, the new owner's property taxes can jump dramatically in the first year after acquisition. That increase gets passed through to tenants in the next reconciliation cycle.
The legal question is whether your lease obligates you to absorb a tax increase caused by the landlord's decision to sell. Most standard leases do not explicitly protect tenants from reassessment-triggered increases, but some do include language limiting tax pass-throughs to increases not resulting from a change in ownership.
If your California building was recently sold and you saw a large unexplained tax spike in the following year, that is the place to start asking questions. Your audit rights allow you to request documentation supporting the tax amounts, including the assessor's notice.
The Lease Language That Protects You
The key provisions to look for in your lease's tax section:
Definition of "Taxes." Does it explicitly exclude special assessments, income taxes, inheritance taxes, franchise taxes? The more narrowly the definition is drawn, the less the landlord can stuff into that line.
Tax appeal language. Does your lease require the landlord to credit back any tax refunds received from appeals? Good leases require this explicitly and specify the timeline for the credit.
Denominator definition. Does your lease specify whether the pro-rata share denominator is the full building or just the commercial portion? If it says "total rentable area," use that number.
Change of ownership. Does your lease include a cap or carve-out for reassessment-triggered increases?
If your lease is silent on any of these, that silence generally benefits the landlord. But it does not mean the landlord's allocation is automatically correct — it means you have to request documentation and verify the math yourself.
How CAMAudit Rule 10 Flags Tax Overallocation
When you upload your lease and CAM statement to CAMAudit, Rule 10 (Tax Overallocation) examines several things automatically:
It extracts the tax definition from your lease and compares it to the line items in the CAM statement. If the statement includes items that your lease definition excludes, the rule flags them.
It reads your pro-rata share denominator from the lease and checks whether the denominator used in the tax calculation matches. A discrepancy here — especially in mixed-use buildings — surfaces immediately.
It also looks at year-over-year patterns. A tax increase that significantly outpaces typical assessment growth in the area is flagged for manual review, which could indicate a recent sale reassessment or an appeal credit that was never passed through.
"Tax overallocation is often the largest single dollar error we flag. The amounts can run into five figures annually because the underlying tax bill is so large. A 10% overallocation on a $200,000 annual tax pass-through is $20,000 per year, every year, until someone catches it." — Angel Campa, Founder of CAMAudit
What to Do If You Suspect a Tax Overallocation
First, pull your lease and read the definition of "Taxes" and "Operating Expenses" carefully. Find the definition section, not just the CAM exhibit — sometimes the exclusions are buried in the general definitions article.
Second, request the supporting documentation for the tax amounts. Under your audit rights, you are entitled to see the actual tax bills, the assessor's notices, and any appeal filings. The landlord should produce these without pushback.
Third, verify the denominator. Ask for the building's total square footage breakdown — how many square feet are commercial, how many are residential or other uses. If the denominator on your reconciliation does not match the total building square footage your lease specifies, you have a claim.
Fourth, check the reconciliation year against any reported property sales in the county assessor's records. Most counties publish sales data publicly. If the building changed hands, you can identify when and look for the corresponding tax jump.
If you find an error, the dispute letter draft CAMAudit generates will reference the specific lease provisions and calculation discrepancies. That letter goes to the landlord's property management team with specific line-item documentation — not a vague complaint.
What Documentation to Request
When you submit a documentation request related to property taxes, be specific. Vague requests get vague responses.
Ask for:
The actual property tax bills. Not a summary — the county-issued bills for each installment paid during the reconciliation year. These show the exact assessed value and the breakdown between land and improvements.
Any appeal filings and settlement documentation. If the landlord filed a tax appeal in the past three years, you want to see the original assessment, the appeal filing, the settlement amount, and the refund received. Then verify that refund was credited to tenants proportionally.
The building square footage schedule. The total rentable area of the building, broken out by use type if it is a mixed-use property. This lets you verify that the denominator in your pro-rata share calculation reflects the full building, not just the commercial component.
The closing or purchase documentation date if the building recently changed hands. You do not need the purchase price — just the date of ownership transfer. With that date, you can check whether a reassessment-triggered increase appeared in the reconciliation year following the sale.
Most landlords will produce this documentation when asked in writing under your audit rights clause. If they resist, that resistance is itself a signal worth noting.
The Statute of Limitations Clock
Knowing you have a claim is not enough. Most states set a statute of limitations of three to five years on contract disputes, and some leases contain shorter audit windows — often 12 to 24 months after the landlord delivers the reconciliation statement.
The discovery rule may extend your window if you can show the error was not discoverable through ordinary diligence. But do not rely on it. The moment a reconciliation statement arrives, the clock starts.
Property tax overallocation is exactly the kind of error that looks clean on paper because the landlord has a real tax bill to show you. The question is never whether the tax was real — it is whether your share of that tax was calculated correctly, and whether the line items on the statement match what your lease actually permits them to charge.
That distinction is worth checking.