I can't even pay the rent this month. I'm flat broke.
be flat broke
slang To have no money. Primarily heard in US. I get paid next week, so can we go out to dinner then? I'm just flat broke right now.I'm flat broke once again and don't know how I'm going to pay my rent.
be flat ˈbroke
(British English also be stony ˈbroke) (informal) have no money at all: I’m afraid I can’t come away with you this weekend — I’m flat broke!