Thanks for the question. This depends on where you are looking in ClinicOffice. When you void an invoice it merely zeros the invoice line quantities and hence it sets the invoice to £0. As you have not deleted it, this means the invoice still exists within the database. If you were to go to something like the Invoice grid or an invoice list this voided invoice will still be present there but merely will display as £0. If you were to go to a report such as Outstanding Invoices you will not be able to view the invoice there.