About Applying Credit Notes and Debit Notes
When you enter credit notes and debit notes using the A/P Invoice Entry screen, you can also specify the number of the document to which the note applies.
If the note applies to several invoices or is issued on account (for example, as a purchase volume rebate), you do not enter an invoice number here. You apply the credit note or "pay" the debit note later, using the A/P Payment Entry screen.
Note: Discounts are not applied to credit notes or debit notes.