A method and system for providing an extensible framework for a POS application is provided. A POS application may be extended using a payment format add-in, a workflow add-in, a financial services provider add-in, or a combination of add-ins. A payment format add-in provides support for a payment format not included in the payment formats built into the POS application. A workflow add-in provides a configurable workflow that can be used to extend a built-in payment format or a payment format add-in. A financial services provider add-in provides support for interacting with a financial services provider for which the POS application does not provide built-in support. Each add-in can implement, for example, logic for processing a payment transaction, a portion of a payment transaction, and configuring steps for processing a payment transaction.