There are 3 methods to create a sales invoice, and 2 types of credit note in EQ. Both invoices and credits are created from the sales order (and always link back to the original sales order). Invoices and credit notes are stored in the same list titled Invoices.
The order value is included on one full invoice.
Part Invoice (Free Type Invoice)
You can free type any amount of the order to invoice. You can have as many part invoices as needed.
If you are splitting the delivery you can invoice just the items that are being delivered. You can have as many part invoices from a delivery as needed.
You can free type any amount of the order to raise a credit note. You can have as many credit notes as needed.
You create a credit note in a similar manner as a quote/order by adding products to credit particular products.
(Read this article for more information about VAT reverse charge on invoices and credit notes)
You can cancel an invoice but this will delete it and the invoice number will not be re-used when you next create an invoice. When you cancel an invoice an entry will be added to the order's progress notes for audit trail purposes.