Select View - Sales/Invoicing and Order registration.
Select Invoiced from the status drop-down list.
Browse to the invoice you wish to credit.
Click Delete.
Answer Yes to the question whether you want to generate a credit note for this invoice.
An unprocessed credit note for this invoice will be created. You can edit it if you need.
Select the Invoice
button in the toolbar to transfer the credit note. If you are informed
that the credit note is unprocessed you will have to go to the Miscellaneous
tab and tick the Processed box.
Select Credit note and Send to printer.
Click OK.
Check the preview. Close preview by clicking Close preview.
The Credit note, update of warehouse window will be displayed. If all products are to be updated in warehouse, click Close.
Answer Yes to invoice the order. The credit note will now be posted.
Answer Yes to approve the printout, if it is correct.
The existing invoice has been credited.