You should talk to your customer about which of the following methods they want to use:
- The Coupa Supplier Portal (CSP), where you sign in to manually flip a PO to create an invoice.
- Supplier Actionable Notification (SAN), where you act on an email without logging in to the CSP.
- cXML, where you can automate the process of sending an invoice file using Coupa's standard cXML format.
- API, where you can automate the process of sending an invoice file using Coupa's API.
- EDI, which is another form of automated invoicing, based on Coupa's standard EDI format.
- Emailed by your customer, which you fill out and send back to them.