Advertised Rental Income

[Preston Brown]

Hey BP! Quick question I'm hoping you can help me understand. 

When looking at properties for sale, I often see something like "Rental income = $1,200". Is this number usually talking about after expenses and mortgage or before the bills are paid? I'm pretty sure any number listed is not accurate either way until I see the actual bills from the property.

I appreciate any insight to help me inderstand what I am not seeing.