The invention comprises a system and method for “waterfall” type payment processing using multiple alternative payment sources. A payor provides account information for multiple payment sources, such as a bank checking account, savings account, first credit card account, second credit card account, and so forth. The multiple payment sources are prioritized so that one is a primary payment source, another is a secondary payment source, another is a tertiary payment source, and so forth. After setting up the waterfall payment arrangement, when a bill becomes due a payee or third party payment administrator submits transactions against the payment sources in their order of priority until the payment is satisfied. Other variations and enhancements are disclosed.