Money in the UFG is officially electronic rather than physical. All money is held by the major banks, under the authority of the UFG, and all purchases are carried out by electronic transfer. Everyone has an electronic cash card which doubles as a personal identity card.
To make a purchase or even to give money to someone else, simply find an electronic cash access point (an E-Cap - there's one at the bar in The Man in Black). Then swipe your card and identify yourself (thumb print or retina scan). Finally, swipe the card of the person receiving the money (or key in their account code if you have it) and key in the amount you wish to transfer.
Of course, all this makes the job of the Federation keeping track of people and capital rather easy, so corporations spend millions finding ways around this. As a result there is, on Jericho-4 at least, a thriving black market economy.
CashOn Jericho-4 and all other places in the UFG where electronic credit transfer just won't do, cash is the way to pay. All cash comes in the form of small gold ingots. Each ingot is worth about 1,000 credits, the credit being the basic unit of Federation currency. Anything smaller than that, and you might as well do a credit transfer, since you can't be doing anything that illegal!
Thanks to the value of cash over credit, if you are attempting to purchase anything illegal, or pay for any illegal services, the basic cost will be at least double if you're paying by electronic credit transfer. You may even find your money being rejected altogether, depending on how worried the other person is about being linked to your bank account. Of course, the more professional criminal elements have false accounts and other methods of concealing their tracks, but all these things cost money to set up and operate.
Naturally, given its untraceability, the possession of even one gold ingot is illegal...
Economics of the gamePut bluntly, there is a finite amount of money in the game and there are certain characters who need various amounts of money to achieve their aims. Needless to say, there isn't going to be enough money going around to satisfy everyone, so be careful with your cash!!
The other source of cash is, of course, property. However, be warned: just because something's worth 1,000 credits doesn't mean you're going to get 1,000 credits for it. The most you can expect for second-hand goods is about half their value, less if they're older or if you're in a hurry to sell. If you're selling something illegal, then you're looking at about 10% of the value...