Interstellar banking is an inherently complicated buisness. Communication lags mean it's possible to be caught off-guard by the collapse of a distant market, and be on the wrong side of currency crash. To avoid this problem, most intra-sector trade is done in a currency of account, even if none of the parties involved use it as their native currency. In the Catacombs this typically the Junction sous. (Equal to one GURPS $, for the ease of book keeping.) The Binf Birr, worth about one-fifth of a Junction sous, and the Nexan shilling, worth about 2 sous, are often used.

Most banking is done in the form of letters of credit. A depositor instructs his bank to transfer some of his funds into an escrow account. In exchange, the bank issues a cryptographically signed letter of credit for the sum. When the depositor arrives in another system, and has need of his funds, he presents a letter of credit at a corresponent bank of his home bank. This second bank sends a validation query to the originating bank; when the response arrives back, the depositor is allowed access to his funds. If the depositor has an existing relationship with the correspondent bank, he may be allowed access to some or all of his funds even in advance of the response.

Ships trading on regular routes usually maintain accounts with banks at their normal ports, to speed their commercial transactions. Passenger ships usually provide some currency transfer services to their passengers, which frees most travellers from worrying about the exact processes involved.