I would look to the financial system of 1600s Europe as a general guide to what the interstellar financial system in the Traveller milieu would look like - generally, monetary transfers between worlds are done by letters-of-credit issued by banking institutions or families that are known and respected at both origin and destination, and accounts are generally periodically balanced by transfer of goods at standard valuations, or by transfer of specie/valuta (however specie/valuta turns out to be defined). Use-currencies are local; the Imperial Credit is a currency-of-account, used for denominating the letters-of-credit and the eventual balancing of accounts, and defining the value of specie or the standard valuations of goods for account balancing.
Imperially-levied taxes are collected at the 'local' level (e.g., by the 'government' of the most local Imperial noble), and generally applied locally, with any surplus or deficit being applied at the balancing-of-accounts level.
Letters-of-credit may be technological in nature (e.g., the equivalent of a smartcard), but need not be; in general, the letter-of-credit will be issued in a form that the destination world can reliably validate.
No banking organization will accept a letter-of-credit issued more than two jumps away (even if issued by a branch of the same organization); only large LICs (subsector-sized or larger) will accept them if issued more than one jump away, and then only if issued by a branch of their own organization or one that they have a specific agreement of exchange with. A Traveller moving along can (and will need to) exchange a letter of credit when moving past the one- or two-jump limit; this is a routine task.
Imperially-levied taxes are collected at the 'local' level (e.g., by the 'government' of the most local Imperial noble), and generally applied locally, with any surplus or deficit being applied at the balancing-of-accounts level.
Letters-of-credit may be technological in nature (e.g., the equivalent of a smartcard), but need not be; in general, the letter-of-credit will be issued in a form that the destination world can reliably validate.
No banking organization will accept a letter-of-credit issued more than two jumps away (even if issued by a branch of the same organization); only large LICs (subsector-sized or larger) will accept them if issued more than one jump away, and then only if issued by a branch of their own organization or one that they have a specific agreement of exchange with. A Traveller moving along can (and will need to) exchange a letter of credit when moving past the one- or two-jump limit; this is a routine task.