The standard unit of currency within the Third Imperium is the Credit. Tendered as coins, notes or high-value credit plaques, Credits are accepted in most places but may have to be converted to local currency in some regions. The Credit is widely accepted beyond the Imperial frontier and is sometimes used as a stable baseline currency to base local transactions upon.
Since there is no faster-than-light communication system other than sending a message aboard a starship and waiting at least a fortnight for an answer, electronic banking is not widely used beyond a local level. Local systems will allow users to draw against funds deposited on-planet or assets pledged as collateral. Large and reputable organisations are generally permitted to draw funds against their reputation, so to speak, as local loans which are then paid in due course.
Large transactions may use hard currency or bearer bonds, or may involve letters of credit. Another common way to handle large transactions is to use physical or economic assets as currency – for example, the ownership of stock in a major corporation or even a starship may be transferred as part of a deal, perhaps as security while the banks on two different planets sort out the details of the cash transaction or as the actual payment.
Operating a financial system over several parsecs and with a lag of weeks is a problem. Faith in the value of the Credit allows cash to be used, which simplifies the problem of electronic transfers between institutions that might be weeks apart by fast courier.