Real Estate Forecasting: Lease Types. The type of commercial real estate lease will dictate how the expenses to maintain, run, and improve the building are shared and paid for. In the Triple Net lease, abbreviated as three Ns, but always called Triple Net, tenants reimburse the property owner for all operating expenses on a pro rata basis. The three Ns refer to net of insurance, taxes, and operating expenses. Almost everything can be considered an operating expense, although utilities are often billed directly to each tenant and never passed through the building owners. These leases are considered the least risky from an owner's perspective. From the tenant's perspective, the ability to control costs is greater in these leases, but there's also the risk of covering all expenses required to keep the building running. In Full Service Gross, or FSG leases, the landlord is responsible for all expenses and covers those expenses by charging higher rent. The rent is often broken down into the rent for the space and the charge for the expenses. Leases in these properties are generally more expensive. The expense passed on to the tenant can be controlled using a term called the base year stop, which sets the increase in expenses to a baseline, such as the first year of rent. Modified Gross leases are a hybrid of the two, in which specific expenses are passed along and some are included in the rent. Base year stops are often features of these leases. These leases can often be called Single Net or Double Net leases, which indicate that they include some of the expenses, but not all of them.