Although it was stated on more than one occasion that the economy of the future was very different, and that money no longer existed in the Federation as late as the 24th century (Star Trek: First Contact) some sort of monetary system still existed and could be accessible to Federation citizens (see Other mentions below).
- James T. Kirk stated that the Federation Starfleet had a lot invested in both him and Commander Spock. In fact, Starfleet had 122,200 plus credits invested in Spock by the end of 2267. (TOS: "Errand of Mercy", "The Apple")
- In 2267, Uhura offered to purchase a tribble from Cyrano Jones for ten credits. (TOS: "The Trouble with Tribbles")
- In 2267, the mirror-universe Kirk attempted to bribe prime-universe Spock with "credits"--indicating that the Terran Empire currency is also referred to as the "credit"--promising that Spock would become a rich man, and that Spock would have a command of his own, in an attempt to gain release from the brig. (TOS: "Mirror, Mirror")
- In 2269, Harry Mudd was selling love potion crystals for three hundred credits a piece before he had realized they actually work. (TAS: "Mudd's Passion")
- In 2364, Beverly Crusher bought a roll of cloth and had her account on the USS Enterprise-D billed. (TNG: "Encounter at Farpoint")
- The Federation would have paid 1.5 million Federation credits as a lump sum and then 100,000 credits every Barzanian year for the rights to the Barzan wormhole. (TNG: "The Price")
- Quark accepted credits in his bar when doing business with Federation citizens. (DS9: "Body Parts", "Take Me Out to the Holosuite"; VOY: "Caretaker")