What happens if you run out of money:

Learn what happens if you run out of money in Sid Meier’s Civilization VII, including how the game prevents bankruptcy by selling your most expensive building.

The game will first warn you that your funds are rapidly decreasing. If there is no other way to prevent you from having a negative number for cash, the game will sell your most expensive building to reduce costs for the next turn.

Having no money means you cannot buy things, incite revolts, or bribe units. It is dangerous to have 0 cash.