In case you and the customer have agreed you will only charge them a portion of the total amount owed for the goods or services initially and request the rest of the money later, you need to reflect this in the invoice. To do it properly, indicate the price of the products or services in the appropriate field and add a field "Notes", "Remarks", or "Payment Terms" to customize the document - in the latter field, you need to clarify the client is paying a certain sum of money upon receiving the invoice, when the goods are delivered, or on a particular date.