What is an office lease audit and how do you know if you're overpaying on operating expenses?
A lease audit is a line-by-line review of your landlord's annual operating-expense reconciliation, the CAM statement, checked against the actual language of your lease. Landlords pass operating costs through to tenants every year, and the reconciliation is where errors hide: capital projects billed as operating expenses, gross-up mistakes, base-year miscalculations on full service gross leases, stacked administrative fees, and charges for costs that fall outside your pro-rata share. Most leases grant you a window to review and dispute these figures, but the clock is short. If the numbers go unchecked, an overcharge baked into one year's reconciliation can quietly repeat for the life of the lease.
You signed the lease. You negotiated the face rate, the free rent, the TI. Then every year a reconciliation statement lands in your inbox, you forward it to accounts payable, and it gets paid. That last step is where the money leaks.
Operating-expense pass-throughs are not fixed. They are calculated by the landlord, reported to you, and trusted by almost everyone. The landlord's property manager builds the statement. The landlord's incentive is to recover as much as the lease arguably allows. Nobody on that side is looking for ways to charge you less.
Here's the truth most tenants never check: the reconciliation is a bill, and bills have errors. Some are honest. Some are aggressive. Either way, you are the one who pays unless you read it against your own lease.
How operating expenses actually flow through your lease
Before you can audit a reconciliation, you have to know which costs your lease lets the landlord pass through. That depends entirely on your structure.
- Full service gross. You pay one rate, and the landlord covers operating expenses up to a base-year amount. You pay your share of increases above that base year. The base-year number is the hinge of the entire deal, and it is a common place for errors.
- Triple net (NNN). You pay your pro-rata share of property taxes, insurance, and common area maintenance directly, on top of base rent. Almost every operating cost flows through to you, which means almost every line is auditable.
- Modified gross. A negotiated split. Some costs sit with the landlord, some pass through to you. Whatever the lease says governs, and the gray areas are where disputes start.
If you are fuzzy on which structure you signed and what it actually obligates you to pay, start with how operating expenses flow through your lease structure. The audit is only as good as your grip on the lease behind it.
The common culprits that inflate your reconciliation
Across the reconciliations I review, the same errors show up again and again. None of them are exotic. All of them cost real money over a multi-year term.
Capital costs billed as operating expenses. A new roof, a chiller replacement, a parking-structure repair, these are capital improvements, not operating expenses. Many leases either exclude capital costs entirely or require them to be amortized over their useful life and passed through in small annual slices. When a landlord drops the full cost of a capital project into one year's operating expenses, your share can spike for no legitimate reason.
Gross-up errors. When a building is not fully occupied, certain variable costs get "grossed up" to what they would have been at full occupancy, so the per-tenant math stays fair. Done right, gross-up protects you. Done wrong, or applied to costs that should never be grossed up, it inflates your share. In a Denver market where downtown office vacancy hit a record near 38.9% in the first quarter of 2026, gross-up math is doing heavy lifting in a lot of buildings, and that makes it worth checking.
Base-year errors on full service gross leases. Your base year sets the floor. If the landlord understates base-year expenses, every dollar of "increase" you pay in later years is calculated off an artificially low starting point. A base year that is wrong by a few percent compounds into a meaningful overcharge across a seven- or ten-year term.
Administrative-fee stacking. Many leases permit an administrative or management fee on operating expenses. The problem is when fees stack: a management fee, plus an administrative fee, plus an overhead charge, sometimes calculated on top of each other. Read what your lease actually allows. One reasonable fee is normal. Three layered fees usually are not.
Management fees on management fees. A specific and common version of stacking. The landlord calculates the management fee as a percentage of total operating expenses, but total operating expenses already include the management fee. The fee gets charged on itself. Small per year, but it recurs every year and it is almost never caught.
Costs outside your pro-rata share. Your pro-rata share is your square footage divided by the building's rentable area. Errors creep in when the landlord understates total building square footage, charges you for costs tied to space you do not benefit from, or bills you for tenant-specific services another occupier received. You should pay your share. Not more.
This is also where occupiers quietly bleed money in ways that never show up on the headline rate. The reconciliation is the same hidden tier as concessions, the place where occupiers quietly overpay because the real cost lives in the structure, not the number they negotiated.
You almost certainly have the right to audit
Most commercial leases grant the tenant an audit or review right: a defined window after the reconciliation is issued during which you can request backup documentation and dispute the figures. The window is often short, sometimes 30, 60, or 90 days, and it can lapse silently. Miss it, and you may waive your right to challenge that year's statement.
Read your lease for the exact language. Look for the audit clause, the notice period, what documentation the landlord must provide, who pays for the audit, and whether a finding above a certain threshold (say, 3% to 5% overcharge) shifts the audit cost back to the landlord. These specifics vary lease to lease, so treat the details as something to confirm against your own lease and counsel, not a rule of thumb.
Reconciliations are issued annually, usually in the first few months of the year for the prior year. That timing matters. If you have not reviewed last year's statement and your audit window is still open, the clock is running right now.
How to audit your reconciliation
You can sanity-check a statement yourself before deciding whether to bring in help. A short version of the method I run:
- Pull your lease and find the operating-expense clauses. Confirm your structure, your base year if you have one, your pro-rata share, the exclusions, and the audit-right window.
- Request the detailed reconciliation and backup. Ask for the line-item statement, not just the summary, plus the prior-year comparison and any invoices your audit clause entitles you to.
- Compare year over year. Flag any line that jumped sharply. A large single-year spike usually signals a capital cost, a one-time project, or an error worth a question.
- Test the big categories against your lease. Check that capital items are excluded or amortized, that gross-up is applied only where permitted, that fees are not stacked, and that the management fee is not calculated on itself.
- Recompute your pro-rata share. Confirm the building's rentable square footage and your percentage. A wrong denominator overcharges you on every line.
- Document discrepancies and notify in writing before your window closes. Put questions in writing, reference the lease section, and preserve your audit right. If the numbers are large or the lease language is dense, bring in a tenant rep or your counsel.
That sequence will catch the obvious problems. The judgment calls, what counts as capital, whether a gross-up is legitimate, whether a fee is permitted, are where experience earns its keep.
When to bring in help
If your annual operating-expense pass-through runs into six figures, the cost of a professional review is trivial next to what a single recurring error compounds to over your term. Bring in help when the reconciliation jumped year over year and you cannot explain why, when the landlord resists providing backup, when capital projects appear in the statement, or when your audit window is about to close and you have not reviewed the numbers.
A finding does not always mean a fight. Often it means a corrected statement and a credit, handled professionally between the tenant's advisor and the property manager. The point is to catch it before it repeats.
Frequently asked questions
What is a CAM reconciliation?
CAM stands for common area maintenance. A CAM reconciliation, more broadly an operating-expense reconciliation, is the annual statement where your landlord trues up estimated operating-expense charges against actual costs for the year and bills or credits you the difference based on your pro-rata share. It is issued once a year, usually for the prior calendar year.
Can I audit my landlord's operating expenses?
In most commercial leases, yes. Lease audit or review clauses grant tenants a defined window to request documentation and dispute the reconciliation. The window is often short, so check your lease for the exact notice period and what backup the landlord must provide, and confirm the specifics with your counsel.
What costs should not be in my operating expenses?
It depends on your lease, but common exclusions include capital improvements (or they should be amortized rather than expensed in one year), costs the landlord recovers from other tenants, leasing commissions, and tenant-specific services. Stacked or duplicated management and administrative fees are also a frequent red flag. Read your specific exclusions.
How often do landlords make reconciliation errors?
Errors are common enough that reviewing the statement is worth doing every year. They range from honest mistakes to aggressive interpretations of the lease. I avoid quoting a single "typical overcharge" figure because it varies widely by building and structure, but a recurring error left unchecked compounds across the full term.
Does this apply to NNN leases or full service gross leases?
Both, in different ways. On a triple net lease, almost every operating cost passes through to you, so nearly every line is auditable. On a full service gross lease, you pay increases above a base year, so base-year accuracy and the calculation of increases are the focus. Modified gross leases follow whatever split the lease defines.
The bottom line
The reconciliation is a bill the landlord writes and you are trusted to pay. Capital costs miscategorized as operating expenses, gross-up errors, base-year mistakes, stacked fees, and pro-rata miscalculations are routine, and a single error baked into one year's statement repeats quietly for the life of the lease. Your lease almost certainly gives you the right to audit, but the window is short and it lapses without warning. Read the statement against your lease every year, and confirm the structure-specific details with your own counsel and CFO before you dispute or pay.
If you're working through a lease decision in Denver, whether that's a renewal, a relocation, or a footprint question your CFO is pushing on, I'm happy to run the numbers with you. Schedule a conversation at calendly.com/mccririe.
About Brian McCririe
Brian McCririe is Executive Managing Director of SVN | Denver Commercial and National Council Chair for Occupier Services across the SVN network. After 25 years representing tenants and investors across global markets, he now focuses on the Denver Metro area helping companies navigate leases, acquisitions, and the gap between what landlords offer and what occupiers deserve. He leads one of the metro's top tenant rep practices and writes about the deals, decisions, and market shifts that matter to corporate real estate leaders.
