The Federation of Koss uses a dual-system currency which hasn't been employed in any macronation.
The St.Charlian Pianeta is the official currency of the Federal Republic of St.Charlie, Koss as a St.Charlian Federation uses such currency, but solely for the purpose of trading with other St.Charlian federation and territories.
Main article: Austral Franc
In it's previous incarnations Koss has helped to build the Austral Economical Union, in which the Austral Franc is the official currency. The currency was kept even though Koss became a St.Charlian state. The Austral franc is used for internal proceedings.