Brief description:  The backup funding servers 218 and 222 include backup funding account information 221 and 225 and backup funding processors 220 and 224. The backup funding account information 221 and 225 can include information about credit accounts, bank accounts, or other accounts from which backup funds can be drawn. In one embodiment, the backup funding account information 221 and 225 can include account holder information (e.g., name, address, etc.), account holder credit limits, and any other suitable account information. The backup funding processors 220 and 224 can process and update the backup funding account information 221 and 225. Additionally, the backup funding processors 220 can also process backup funding requests for transactions associated with the account server 212. FIG. 8 is a flow diagram illustrating operations for selecting between different backup funding sources, according to example embodiments of the invention. The flow diagram 800 will be described with reference to the system architecture shown in FIG. 2. The flow begins at block 802.  At block 802, an account server's backup funding unit 214 presents an option to change a backup funding source associated with an account. For example, in an online retail transaction in which an account holder is making payment with a debit card, the backup funding unit 214 presents a payment interface (e.g., a web page) that allows the account holder to select a new backup funding source for that retail transaction. Alternatively, the backup funding unit 214 can present the payment interface anytime after the transaction processor 216 determines that backup funding is needed and that the account is associated with backup funding (e.g., after block 406 of FIG. 4). In one embodiment, the account holder can select between previously verified bank accounts, previously verified credit card accounts, and previously verified lines of credit. The flow continues at block 804.  At block 804, the account server's backup funding unit 214 receives a selection indicating a new backup funding source. For example, the backup funding unit 214 receives a backup funding source selection through the payment interface presented at block 802. In one embodiment, the buyer can select more than one backup funding source. From block 804, the flow continues at block 806.  At block 806, the account server's backup funding unit 214 changes the account's backup funding source based on the selection. In one embodiment, the backup funding unit 214 modifies information in the account information unit 215 to reflect the newly selected backup funding source. From block 806, the flow ends.