Common Area Maintenance (CAM) fees are the portion a tenant pays to maintain common areas such as lobbies or courtyards, which every tenant in the building shares. The fee covers costs including landscaping, cleaning, janitorial service and maintenance, like new paint or flooring. These costs are averaged out on a per year basis. Each tenant's share of CAM depends to the square footage rented in relation to the entire square footage of the building. Tenants who operate out of smaller spaces usually pay less for CAM, while those in larger spaces pay a greater share.
Determine the Gross Leasable Area (GLA) of the property, or the amount of a building's square footage that can produce income through a lease.
Find the square footage leased by each tenant.
Divide the tenant's square footage by the GLA. If the tenant leases 3,000 square feet and the GLA is 100,000 square feet, the equation looks like this: 3,000 / 100,000 = .03. Multiply by 100 to change the decimal to a percent. This percentage represents the proportion of the CAM fees to paid by that particular tenant. In this case, the tenant would be responsible for 3% of the costs.