Sale Advance Payment

This module adds advance payment handling to sales orders. On a sales order form, users with invoicing rights see a new "Pay sale advanced" button next to the standard buttons, plus a "Payment advances" tab listing the payments linked to that order.

Clicking the button opens an "Advance Payment" pop-up where you choose the payment method (bank or cash journal), the payment type (inbound or outbound), a reference, a date and the amount to advance. The order's due amount is shown for reference, and the amount is converted into the order currency automatically. The system refuses a zero or negative amount, an inbound advance larger than the order's residual amount, or an outbound advance larger than what was already paid. Confirming creates and posts a customer payment linked to the order.

The sales order then displays a computed "Residual amount" and an "Advance Payment" status badge (Not Paid, Partially Paid, Paid), also available as optional columns in the quotations and orders lists. When an invoice for that order is posted, any outstanding advance payment linked to the order is automatically assigned to the invoice. The module touches sale.order, account.payment and account.move.