CAM Audit Before Signing a Lease: How to Verify CAM History During Due Diligence

TL;DR: Before signing any NNN or gross-modified lease, request 3 years of CAM reconciliations from the landlord and run them through a forensic audit. Forty percent of commercial reconciliations contain material billing errors. A $79 pre-signing audit tells you how this landlord actually bills before you are contractually obligated to pay them.

pre-signing CAM audit: A pre-signing CAM audit is a forensic review of a commercial property's historical CAM reconciliation statements conducted by a prospective tenant during lease due diligence, before signing. The purpose is to evaluate how the landlord applies CAM billing provisions in practice, identify any systematic overcharges in the prior tenant's reconciliations, and use findings to negotiate protective lease language before execution.

Signing a lease without reviewing prior CAM reconciliations is the commercial real estate equivalent of agreeing to a pricing model you have never seen. The lease form describes how CAM will be calculated. The reconciliation history shows how it actually has been calculated. Those two things are not always the same.

The pre-signing period is the only time you hold full negotiating leverage. After execution, every protective clause you failed to include becomes a gap the landlord fills with their own billing practices. The standard lease form is drafted by the landlord's attorney. If you do not negotiate specific language based on specific evidence, you are accepting their defaults.

40% of commercial CAM reconciliations contain material billing errors (PredictAP, 2026)

Why most tenants skip pre-signing CAM due diligence

Most tenants never think to request historical CAM reconciliations before signing. The pre-signing conversation is about base rent, TI allowance, lease term, renewal options. CAM charges feel secondary while you are negotiating the headline numbers.

That framing is expensive. In a 5,000 square foot retail or office space, annual CAM charges often run $8 to $25 per square foot. On a 5-year lease, the cumulative CAM exposure can match or exceed the total TI allowance. Treating it as secondary means skipping the due diligence on one of the largest variables in the deal.

There is also a common assumption that the CAM provisions in the lease form govern what you will actually pay. They do not, not entirely. The lease sets the framework. The landlord's billing practices determine how that framework gets applied year to year. A management fee cap of 5% is only as protective as the landlord's willingness to honor it. A gross-up provision is only as useful as the occupancy threshold they actually use. Prior reconciliations show you the gap between what the lease says and what the landlord does.

And requesting reconciliation history is not adversarial. Any landlord with clean billing practices will hand it over without hesitation. If they won't, that tells you something too.

The due diligence document request: what to ask for and when

Request these documents during the LOI negotiation or immediately upon entering the formal due diligence period:

Three years of annual CAM reconciliation statements for the space you are leasing (or the prior occupant's comparable space). If the building is a new construction or the prior tenant occupied for less than 3 years, request whatever is available.

The most recent annual reconciliation for the full property, not just your suite. This lets you verify the expense pool total and check whether excluded expense categories are appearing in the pool.

A copy of the prior tenant's lease CAM exhibit (or the current standard CAM exhibit being offered to you). Comparing the exhibit language to how it was actually applied in the reconciliation reveals any gap between stated terms and billing practice.

Documentation for any major capital expenditure years. If the reconciliation shows a sharp cost spike in a given year, request the backup for that year specifically. Capital expense reclassification into operating expense pools is one of the most common sources of material overcharges.

The right moment to make this request is before you sign the LOI, or immediately after, while the due diligence period is still open. Frame it as standard financial due diligence, because that is exactly what it is.

What a pre-signing CAM audit reveals

Running 2-3 years of prior reconciliations through CAMAudit surfaces five specific things about the landlord's billing practices:

1. Whether the management fee has historically matched or exceeded the proposed cap. The lease may offer a 5% management fee cap, but if prior reconciliations show the landlord consistently billing at 4.8 to 5% of controllable expenses, you are already at the ceiling with no cushion. CAMAudit's management fee overcharge rule checks whether the billed amount exceeds the defined cap.

2. Whether excluded expense categories appear in the pool. Most standard CAM exhibits exclude capital expenditures, depreciation, and landlord corporate overhead. Prior reconciliations often contain expense line items that belong in those excluded categories but were passed through anyway. CAMAudit's excluded service charges rule flags these by category.

3. How gross-up is applied. Gross-up provisions adjust operating expenses to reflect a hypothetical fully-occupied building. The provision should protect you from absorbing vacancy costs, but it only works correctly if the occupancy threshold and calculation method are applied as written. Reconciliations from low-occupancy years are particularly useful here.

4. Whether the pro-rata share denominator has shifted across years. A denominator that shrinks over time, even while the building's physical footprint stays constant, is a signal that the landlord is using a leased-and-occupied denominator instead of a total leasable denominator. That shift inflates every tenant's share. Comparing the denominator across 3 years of reconciliations makes this visible immediately.

5. Whether year-over-year CAM expense growth follows a reasonable pattern. Expense pools that grow faster than CPI in years with no major capital events point to expense reclassification, management overhead pass-through, or a controllable expense cap being applied inconsistently. CAMAudit's CAM cap violation rule checks for this.

How to convert audit findings into protective lease language

Here's where the audit earns its $79. Pre-signing findings are not just informational: each one maps to a specific lease clause you should negotiate before execution.

Management fee consistently billed near the proposed cap. Push for an explicit cap expressed as a percentage of controllable expenses, not total CAM, with a written definition of what qualifies as a management fee. Without that definition, landlords can reclassify overhead as a management service and stay technically within the cap while billing more.

Capital expenditures appearing in the pool. A general exclusion clause is easier to argue around than a named list. Get the lease to list specific categories: capital expenditures, depreciation, building improvements, structural repairs. The more specific the list, the harder it is to pass through items that don't belong.

Pro-rata share denominator changed between years. Get the actual square footage number written into the lease as a fixed denominator. If it can only change via written amendment, the landlord cannot quietly shrink it as other tenants vacate.

Gross-up applied at an unusual occupancy threshold. Set the threshold explicitly (90 to 95% is standard), name which expense categories are subject to gross-up and which are not, and specify the calculation method. Vague gross-up language is where a lot of disputes originate.

Year-over-year expense growth above 8 to 10% with no capital event. Negotiate a controllable expense subcap, separate from any overall CAM cap, limiting annual growth to something like 5% compounded. This targets management-driven inflation rather than just spike years.

If the findings are bad enough, a rent concession or walking away may be the right call. A landlord who has been overbilling the prior tenant does not typically change billing practices for the next one.

What to do if the landlord refuses to provide prior reconciliations

A landlord who refuses to provide prior reconciliation history during due diligence is sending a signal. Either the reconciliations contain billing practices they would prefer you not see, or they operate on a policy of information asymmetry and expect tenants to accept CAM charges on faith. Either way, you have learned something useful about who you are about to do business with.

Your first step is to ask formally and in writing, even if you have already asked verbally. A written refusal is documentation. A verbal "we don't typically share that" is easier to walk back.

If the landlord cites confidentiality, that objection does not hold: the reconciliation is your expense history, not a third-party's trade secret. You can propose a confidentiality agreement covering the documents if that removes the objection.

If the refusal persists, you have three options.

Option 1: Negotiate a first-year CAM cap. Add a lease clause capping your CAM exposure at a fixed dollar amount per square foot for the first lease year, with a defined maximum annual increase. This transfers the risk of historical billing irregularities onto the landlord's side of the ledger.

Option 2: Negotiate an enhanced audit rights clause. Request a 4-year lookback period instead of the standard 2 to 3 years, annual audit rights with no notice threshold required, and a tenant-friendly remedy provision if errors are found.

Option 3: Walk away. A landlord who will not show you the billing history before you sign is unlikely to respond constructively to a dispute letter after you do.

Lease renewals are pre-signing moments too

When your lease is up for renewal, you are negotiating new terms before signing a new agreement. Run the final 2 to 3 years of the expiring lease through a pre-signing audit before renewal negotiations open.

Two things come out of it. Any overcharges in the expiring term become negotiating leverage: landlords frequently prefer to credit the amount against new lease terms rather than defend it in a formal audit. And the billing patterns you find tell you exactly which lease clauses need tightening before you sign again.

"I built CAMAudit because the leverage gap between pre-signing and post-signing is enormous. Before you sign, you can negotiate anything. After you sign, you are filing dispute letters and hoping. Running a $79 audit on prior reconciliations before you execute a lease is the cheapest due diligence step available in any commercial real estate transaction." — Angel Campa, Founder of CAMAudit

A renewal audit also gives you a concrete number to anchor the negotiation: if CAMAudit identifies $12,000 in overcharges across the final three years of the expiring lease, that number belongs in the first renewal negotiation meeting. It is not an accusation; it is evidence. Most landlords will either provide a credit or adjust the new lease terms rather than dispute a documented finding from a forensic audit.

15-20% of total billed CAM is typically recovered when tenants conduct first-time audits (PredictAP (citing Springbord industry analysis), 2026)

Consider the cost gap. Traditional audit firms charge $2,500 to $15,000 per property, before a 30 to 33% contingency fee on top. A CAMAudit scan on prior reconciliations costs $179, runs in under 15 minutes, and produces a finding report you can bring to the negotiation table that same day.

Signing a lease without reviewing the CAM history means agreeing to a pricing model you have never examined. It may be fine. It may not. The difference between knowing and not knowing is $79 and 15 minutes, but only before you sign.

Frequently Asked Questions

Can a prospective tenant request CAM reconciliation history before signing a lease?

Yes. Requesting 2-3 years of prior CAM reconciliations is a reasonable due diligence request during LOI or lease negotiation. Most landlords with clean billing practices will provide them. A landlord who refuses to provide prior reconciliations is signaling either billing irregularities or a policy of keeping tenants uninformed. That refusal itself is useful information.

What does a pre-signing CAM audit reveal?

A pre-signing CAM audit on historical reconciliations reveals how the landlord actually applies the CAM provisions in the standard lease form: whether management fees have historically exceeded the cap, whether capital expenditures appear in the expense pool, how gross-up is applied, and whether the pro-rata share denominator has changed across years. This tells you what you are actually agreeing to, not just what the lease form says.

How many years of CAM history should I request before signing?

Request at least 3 years of CAM reconciliations if available. One year may reflect an anomalous period. Three years shows the landlord's billing pattern across different occupancy levels and operating expense cycles. Pay particular attention to years when major capital projects occurred, since capital expense reclassification into CAM is the most common pattern in overcharge cases.

What lease language protections should I negotiate based on pre-signing audit findings?

Based on pre-signing audit findings, negotiate: an explicit management fee cap (if the landlord's historical rate is at or near the proposed cap), a list of excluded expense categories (if prior reconciliations include items that should be excluded), an audit rights clause with a specific lookback period (2-4 years), a CAM cap or controllable expense subcap, and a gross-up cap at a defined occupancy threshold.

Is a pre-signing CAM audit useful for lease renewals too?

Yes. A pre-signing audit is equally applicable to lease renewals, when the tenant is negotiating new lease terms. Auditing the final 2-3 years of the expiring lease before renewal negotiations identifies overcharges that can be used as leverage and reveals billing patterns that should be addressed in the new lease language.

CAM Audit Before Signing a Lease: How to Verify CAM History During Due Diligence