Selecting payment instruments for proxy card transactions comprises associating a plurality of financial accounts with a user proxy account; establishing a model for the user account based on configuration data received from a user, the model comprising identification of a particular financial account to use as a backing instrument for a transaction; receiving data associated with a pending transaction regarding the pending transaction; identifying a financial account to use as a backing instrument for the pending transaction based on a comparison of the model with the pending transaction data; receiving a selection of an alternate financial account to use instead of the identified financial account as the backing instrument; modifying the model account based on the selection of the alternate financial account and the data associated with the pending transaction; and utilizing the modified model in a subsequent selection of a financial account for a subsequent transaction.