A user can customize use of a payment card, which can be an electronic card, by selecting a customization variable for any given transaction. The customization variable involves at least one of the following steps: (1) customizing generation of a one-time card number; (2) customizing a user identifier; or (3) inclusion of a customization variable with information transmitted to a verification agency for validation of the given use. Multiple payment card transactions can be processed differently depending upon which customization variable is chosen for a given transaction. Different customization variables can be used for different accounts, different types of transactions, or to classify the transactions. A user can receive one bill, or multiple bills. Different levels of privacy can be accorded to transactions that use different customization variables. A user may pay the issuer for increased security, or the user may be paid by the issuer to allow transaction data to be distributed to third parties.