Gross income is the total amount of income you can get in a property. This is important to understand because this number isn't necessarily guaranteed. For example, if a property has 4 units that rent for $500 a month, the gross income would be $2,000 a month. However, this property may only be partially rented.
Having a property only partially rented could be a bonus if the purchase price reflects the occupancy status. In other words, if you buy the property and make do what it takes to make it fully rented, you can increase the value of the property quickly.
In addition to rent, other items such as coin operated laundry, storage fees, late fees, vending machines, etc, can be factored into gross income.
Top Ten Terms for Commercial and Investment Real Estate