Flat broke
Definition 1 of 1
Pro Tip 1/3Complete Lack
Emphasizes having absolutely no money, even for basic needs. 
After the trip, I was flat broke and couldn't even afford a bus ticket home.
Pro Tip 2/3Informal Usage
Used in casual settings among friends or family, not in formal contexts. 
Can't join you for dinner tonight, I'm flat broke until payday.
Pro Tip 3/3Temporary State
Often used to describe a temporary financial situation, not permanent poverty. 
Spent all my savings on repairs; I'm flat broke this month.