Assignment of transactions to sub-accounts in payment account system

A method comprising:

• receiving a transaction authorization request message, the transaction authorization request message including first data in a payment account number field in the transaction authorization request message, the transaction authorization request message corresponding to a purchase transaction;
• replacing the first data in the payment account number data field with second data, the second data including a payment account indicator;
• and
• routing the transaction authorization request message to an account issuer based on the second data, the payment account indicator associated with a payment account issued by the account issuer;
• the routed transaction authorization request message including sub-account indicator data for indicating to the account issuer that the purchase transaction is to be assigned to a sub-account associated with said payment account.

A method comprising:

• opening a wallet application in a payment-enabled mobile device, the wallet application for allowing a user to access a digital wallet;
• prompting the user to select from among at least two sub-accounts associated with a payment account that the user intends to select for use in a current transaction;
• receiving a sub-account selection signal from the user, the sub-account selection signal indicating selection of one of said at least two sub-accounts;
• and
• transmitting payment credentials from the payment-enabled mobile device to a POS (point of sale) terminal, the transmitted payment credentials indicative of said selection of said one of said sub-accounts.