Invoices are an essential part of any business and should be given their due attention. Without invoices, after all, a business would not receive payment for services rendered. The (1)............... of the invoice must be stated clearly, that is, the customer needs to know exactly what he is being charged for and when the payment is due. If a customer discovers a mistake on the invoice, it should be rectified as soon as possible. If a final charge is much greater than the original estimate, the reason for this should be explained as clearly and simply as possible on the invoice. Some businesses (2)............... a late fee on late payments. In such cases, this must also be made clear on the invoice. Finally, the invoice must be sent to the customer (3)............... in order to encourage timely payment.