I work for a skip company and open an invoice when a skip is hired. The invoice is not completed until it returns to the site and a tipping charge added. It would be very useful for me if the date of the invoice changed when the invoice has items added to it as when I do an invoice run, It is very time consuming to change the date manually on the invoice and sometimes I forget, so if a skip has been out on hire for some months, the date of the invoice is wrong for tax purposes for the customer.