Gross Income is the maximum amount of money that an income property can collect. For apartment buildings, this means rent. Income from Laundry machines and Storage, as well as other sources, may be added to the Gross Income for buildings with these additional revenue streams.
100-unit apartment building where each unit is expected to rent for $500 per month:
x $500 rent/mo.
x 12 months
$600,000 Gross Income
Gross Income assumes 100% occupancy. Obviously, real estate will have vacancy from time to time. This is not factored in Gross Income calculation.