A pro-rata share is the percentage of a property attributable to a single tenant, used to allocate recoverable expenses like CAM, taxes, and insurance. It is most commonly calculated as the tenant’s rentable square footage divided by the property’s (or building’s) total rentable square footage. Leases may define the denominator differently — total building area, occupied area, or a fixed share — which materially affects how much each tenant pays, so the definition is a key negotiation point.
Pro-Rata Share = Tenant Rentable SF ÷ Total Rentable SF
Why the denominator matters
How the share is defined changes the allocation:
- Total building SF — divides costs across all space, occupied or not
- Occupied SF — divides only among current tenants (raises each share)
- Fixed share — a negotiated percentage that does not move with occupancy
Pro-rata share in reconciliation
During a CAM true-up, the landlord applies each tenant’s pro-rata share to total recoverable expenses to determine that tenant’s portion. An accurate, consistent share is essential to a defensible reconciliation.
A tenant leases 8,000 rentable square feet in a 100,000-square-foot building. Their pro-rata share is 8,000 ÷ 100,000 = 8%, so they bear 8% of recoverable expenses.