What is a Credit Note? A Credit note is a document sent from a business to a customer, informing the customer that money has been added to the customer's account. Credit notes are typically used when products are returned, goods delivered are damaged, or mistake in the invoice.
In Odoo you can issue a credit note from scratch by going to Accounting ‣ Customers ‣ Credit Notes, and by clicking on Create. Fill the Credit Note’s form the same way as the Invoice’s form.
However, most of the time, credit notes are generated directly from the invoices they are related to.
To do so, open the Customer Invoice, and click on Add Credit Note.