Automatic invoice notification

Introduced here is a technology for automatic notification of an invoice for a customer based on identification of a customer identifier included in transaction data received from a point-of-sale (POS) system of a particular merchant ("the invoice technology"). The notification can include a promotion to provide an incentive to the customer to pay the invoice. The notification can be presented on a display of the POS system. Alternatively, the notification can be presented in a receipt for the transaction conducted at the POS system, where that receipt can be transmitted for display at a user device of the customer. For example, the receipt can be in the form of an email message or a text message. Upon notification of the invoice, the customer can submit a payment for that invoice ("invoice payment") in exchange for the promotion.