Your space
What area does the signed lease assign to your premises?
Lease premises clause · amendments · floor plan
CAM and NNN allocation guide
Your share starts with the right denominator.
Pro-rata share is the percentage used to assign some property costs to a tenant. The simple math matters, but the signed lease decides which spaces, expenses, and allocation method belong in it.
The illustrative formula
Tenant area
2,500 sq ft
Defined property area
25,000 sq ft
Illustrative share10%
This common formula is an example. Your lease may define the denominator or cost pool differently.
See the difference
Same space. Different area. Different share.
If the denominator changes from 25,000 to 20,000 square feet, the arithmetic changes even though your 2,500-square-foot space does not. The question is which area the lease requires for that expense pool.
Illustrative comparison only. Neither percentage is automatically correct or an overcharge.
Two possible denominators
Scenario A
2,500 ÷ 25,000
10%
Scenario B
2,500 ÷ 20,000
12.5%
What to verify
The lease-defined area, any separate cost pool, and the property area schedule used on the annual statement.
Try the math yourself
Change the inputs. See why the area matters.
Enter a leased area, a property area, and an illustrative expense pool. The calculator shows the simple square-footage share and its portion of that pool.
Use the figures your lease and area schedule call for. This exercise does not verify a statement or determine whether a charge is allowed.
Illustrative share calculator
Illustrative share
10%
Share of entered pool
$10,000.00
For illustration only. The lease may use a different area or allocation method. This result does not account for exclusions, caps, credits, or other adjustments, and it is not a bill or an overcharge estimate.
Five allocation checks
Make the percentage traceable.
A percentage on the statement is easier to evaluate when you can connect it to a lease clause and the area or cost records behind it.
The denominator
Which property area or cost-pool area does the lease say to use?
Property area schedule · cost-pool description
Vacancy and exclusions
Does the lease change the denominator or allocation when space is vacant or separately served?
Lease allocation clause · occupancy schedule
Different expense pools
Are CAM, taxes, insurance, or particular services allocated using different methods?
Annual statement · category ledger · allocation worksheet
Year-to-year changes
Did your percentage change, and what lease event or area change explains it?
Prior and current statements · updated area schedule
Keep the distinction clear
A mismatch is a question.
It becomes a supported conclusion only after comparing the signed terms, billed calculation, and underlying records.
Use the right sequence
From percentage to a useful question.
Step 01
Read the clause
Identify the lease's exact area definition, expense pool, and any adjustment rules.
Step 02
Check the statement
Write down the percentage used for each billed category and year.
Step 03
Request the schedule
Compare area and allocation records, then note any difference that needs an explanation.
Watch the review procedure
Your lease controls how to ask for records.
If the statement does not explain the percentage, check the lease's notice and records-access terms before requesting the property area schedule or allocation worksheet. A report does not send a notice for you.
Continue learning
Related guides.
CAM reconciliation
Trace costs, tenant share, estimates, and credits through an annual true-up.
Read the guide ↗Expenses to check
Investigate cost categories using the lease and supporting records.
Read the guide ↗Common questions
Before you draw a conclusion.
Is pro-rata share always square footage divided by total leasable area?
No. That is a common illustration, but the signed lease may define a different area, cost pool, or allocation method. Use the agreement's actual formula.
Does a different denominator prove an overcharge?
No. It raises a question. Compare the number used with the lease definition and the supporting area schedule before drawing a conclusion.
Can a lease preview verify the billed share?
A preview may surface the lease's allocation terms. Verifying a billed percentage also requires the annual statement and, often, the area or allocation records.
When should I ask for the area schedule?
If the statement does not show enough detail to explain the percentage, check the lease's records-access procedure and request the relevant schedule within any applicable deadline.
Your next step
Start with your lease's share clause.
A free lease preview can surface allocation terms and initial questions. Add the annual statement and supporting PDFs if you have them to compare the billed details before deciding whether a full report is useful.