The Mafia Boss/Bank

Safe box
The safe box is a place to deposit money to keep it safe from attacks. It costs 15 turns to deposit money. There is currently no option to choose how much is deposited; the amount deposited will always be 15% of your cash on hand. If you already have money in the safe box, you must withdraw it first before re-depositing.

Transfers
Use transfers to send money to other players. In Round 22, a limit of 25% of your total cash on hand was imposed, as well as a 15 turn fee per transaction. Previously, it was free to send money, and you could send 100% of your available cash.

Mafia pawn
Use the Mafia Pawn to exchange turns directly for cash, at a rate of $500 per turn. This is almost never worth it, as you can easily earn exponentially more than $500 per turn using other methods unless you have very few operatives and defensives.