The gross-up provision is one of the more counterintuitive clauses in a commercial lease. On its face, it benefits tenants. In practice, it's one of the more common sources of CAM overcharges I see when running reconciliations through CAMAudit.
Understanding how gross-up is supposed to work — and how it gets misapplied — starts with a basic question: what happens to a building's operating costs when it isn't fully occupied?
Why Gross-Up Exists
Some costs go up and down with occupancy. Electricity for tenant spaces, water consumption, janitorial services for occupied floors — these costs actually decrease when tenants leave. If the building is half-empty, the landlord genuinely spends less on these services.
Now consider the tenant's perspective. If the landlord collects CAM charges to cover actual variable costs, a half-empty building produces lower total costs — but the remaining tenants bear a disproportionately large share of those reduced costs, because their pro-rata share denominator may have shrunk. And next year, when the building fills back up, the per-square-foot cost drops again. Tenants end up on a CAM billing roller coaster tied to the landlord's leasing success.
Gross-up solves this by normalizing variable costs. The provision says: calculate what these costs would have been if the building were at a specified occupancy level (often 95%), and use that figure in the CAM pool rather than actual costs.
The result is a stable, predictable per-square-foot cost that doesn't spike just because the landlord has vacancy — and doesn't drop artificially during high-occupancy periods in a way that might prompt the landlord to under-provide services.
That's the legitimate purpose. The problem is execution.
How Gross-Up Should Work: An Example
Your building has 200,000 rentable square feet. Actual occupancy during the year is 78%. Variable costs — primarily HVAC, utilities, and janitorial services for common areas — came in at $620,000.
The gross-up provision specifies 95% occupancy. The landlord's calculation:
Gross-up adjustment: $620,000 actual ÷ 78% occupancy × 95% threshold = $755,128 gross-up amount
Your share is 2.5% of the building (5,000 square feet out of 200,000). So your CAM portion attributable to these variable costs is $755,128 × 2.5% = $18,878.
Without gross-up, using actual costs: $620,000 × 2.5% = $15,500. The gross-up increased your charge by about $3,378.
From the landlord's perspective, that's justified — next year the building might be at 95% and these same costs will genuinely be $755,000. The provision smooths the billing across occupancy cycles.
But notice what the calculation hinges on: the identification of which costs are "variable" and eligible for gross-up, and the correct occupancy percentage. Both of these are where errors — and deliberate misapplications — occur.
Three Common Gross-Up Violations
1. Grossing Up Fixed Costs
Property taxes don't change based on occupancy. Insurance premiums (for the building itself) don't change based on occupancy. Certain structural maintenance contracts don't change based on occupancy.
These are fixed costs. The gross-up provision applies to variable costs — those that would actually increase if the building were more fully occupied. Applying the gross-up formula to taxes and insurance artificially inflates the cost pool with an adjustment that has no relationship to actual service levels.
In the example above: if the landlord incorrectly applies gross-up to $280,000 in property taxes and insurance, those costs get inflated to $340,000+ even though the landlord paid exactly $280,000 regardless of occupancy. The tenant gets billed for a fictional increase.
This is the most common gross-up violation I see. Reconciliation statements usually don't break out which costs were grossed up — they present a total CAM pool with a single gross-up line or an aggregate figure. Tenants can't identify the problem without the underlying backup.
2. Wrong Occupancy Base
The gross-up formula divides actual costs by actual occupancy and multiplies by the threshold occupancy. A small error in the occupancy denominator produces a material billing error.
Common versions of this problem:
Using the wrong occupancy date. Occupancy varies throughout the year. Whether the landlord uses average occupancy, year-end occupancy, or some other measure can significantly change the calculation. Your lease should specify which method applies.
Conflating different occupancy figures. The denominator for the gross-up calculation and the denominator for the pro-rata share calculation may differ under your lease. If the landlord uses the same figure for both, one of them is wrong.
Including the anchor's space in one calculation but not the other. After a large tenant vacates, the landlord may gross up as if that space is occupied (inflating the cost pool) while also using a smaller denominator for your pro-rata share (increasing your percentage). These two adjustments, applied simultaneously, can compound the overcharge substantially.
3. Gross-Up Applied When Occupancy Already Exceeded the Threshold
Some leases permit gross-up only when actual occupancy falls below the threshold. The provision might read: "If the Building is not at least 95% occupied during any calendar year, Landlord may gross up variable CAM expenses to reflect 95% occupancy."
Read carefully: the condition is that occupancy must be below 95%. If the building is at 96% occupancy, the provision doesn't apply. Costs are billed at actual.
Where does this go wrong? When occupancy fluctuates through the year. A building that averaged 91% annual occupancy might have been above 95% for several months. Depending on how your lease defines the measurement period, gross-up may only be appropriate for portions of the year, not the full annual period.
More concretely: if the lease threshold is 95% and the building hit 97% during the summer months (its peak occupancy period), those months should not be grossed up. If the landlord applies an annualized gross-up to the full year's costs, some portion of that adjustment is unauthorized.
The Math of a Typical Gross-Up Overcharge
Let me show what this looks like in dollar terms. A mid-size office tenant leases 6,000 square feet in a 150,000-square-foot building. Their pro-rata share is 4%.
Annual CAM pool, as presented in the reconciliation: $1,850,000 (after gross-up).
What the landlord did: grossed up the entire cost pool — including $410,000 in property taxes and $190,000 in building insurance — using an 80% occupancy denominator and a 95% threshold.
Incorrect calculation (landlord's method): $1,850,000 total pool × 4% = $74,000 tenant charge
Correct calculation (gross-up applied only to variable costs): Fixed costs (taxes + insurance): $600,000 — no gross-up Variable costs: $850,000 actual ÷ 80% × 95% = $1,009,375 grossed-up variable Corrected pool: $600,000 + $1,009,375 = $1,609,375 Tenant charge: $1,609,375 × 4% = $64,375
Difference: $9,625 overcharged in a single year. Over a 5-year lease, that's $48,125 — before accounting for compounding, management fee markup on the inflated pool, or other cascading errors.
What to Look for in Your Lease
Your lease's gross-up provision (if it has one — not all leases do) should specify:
Which costs are eligible. Look for language like "variable operating expenses" or "costs that vary with occupancy." If the provision doesn't limit eligible costs by variability, that's a problem the landlord can exploit.
The threshold occupancy level. Common values are 90%, 95%, or 100%. Whatever your lease says, the landlord can only gross up to that level, not beyond.
The trigger condition. Does the provision apply whenever occupancy is below threshold, or only under specific circumstances?
The measurement method. Average annual occupancy? Point-in-time? What counts as "occupied" — only leased space, or space under a letter of intent, or space in buildout?
Who determines the variable/fixed classification. Some leases give the landlord discretion to classify costs. Others list specific expense categories.
If your lease is silent or ambiguous on any of these points, you have a gap — and the landlord's reconciliation will fill that gap in their favor unless you challenge it.
How CAMAudit Flags This
When I built the gross-up detection rule in CAMAudit, the goal was to catch the cases that aren't obvious on the face of the reconciliation statement.
The tool checks whether the gross-up adjustment in the presented reconciliation is consistent with the lease's specified threshold and eligible cost categories. It compares the gross-up factor implied by the reconciliation against what the stated occupancy figures would produce. When the numbers don't reconcile — when the implied adjustment would require applying gross-up to costs that don't move with occupancy, or when the factor is larger than the lease threshold would justify — it flags the discrepancy.
For the tenant, the output is specific: which line items appear to have been grossed up incorrectly, what the adjustment was, and what it should have been under a faithful reading of the lease.
40% of CAM reconciliations contain material errors (Tango Analytics, cited by PredictAP, 2023)
Gross-up is one of the categories most likely to contain a material error because it requires the landlord to make judgment calls about cost classification that affect the total billing. Those judgment calls aren't always made in the tenant's favor.
Putting It Together
The gross-up provision was designed to stabilize CAM costs for tenants in under-occupied buildings. When it works correctly, it does exactly that — your per-square-foot cost stays predictable whether the building is at 78% or 95% occupancy.
When it's misapplied, it becomes the mechanism for systematically overbilling tenants in ways that are nearly impossible to detect without checking the underlying math against lease language.
70% of commercial tenants identify billing discrepancies when they audit (Deloitte, 2024)
The CAM reconciliation statement doesn't tell you whether gross-up was applied correctly. It tells you what you owe, and if you don't question it, you pay it.
The question is whether your landlord applied the provision the way your lease defines it. Running that check takes knowing your lease's specific language, the correct variable/fixed cost classification, the occupancy figures for the period, and the arithmetic. That's exactly what CAMAudit was built to do — flat fee, under 15 minutes.
"Gross-up is probably the hardest common error to spot manually because it requires checking the cost pool composition, not just the top-line number. That's what the tool looks for specifically." — Angel Campa, Founder of CAMAudit