Because invoice factoring is a unique form of financing there are important considerations concerning how your business model operates. How you set up your deals with customers is more important than you might think. Just a slight change in the way you bill for your services could make or break the ability to secure financing on the accounts receivable.
If your business provides a service you should always specifically outline the work to be done and create deliverables or milestones that allow you to invoice. From a factoring standpoint, this is much more preferable than billing along the way or progress billing. By completing a milestone the customer is obligated to pay for something that they received. With progress payments the risk is the customer becomes upset with the work and stops making their usual payments.
The way invoice factoring works is the factor must be able to independently, if needed, go after the account debtor (customer) for payment of the invoice. This means that the work has to be completed and acceptable to the customer. Then the customer has no legal reason not to pay the invoice in full, and could be asked to defend non-payment in court. With a progress payment there is too much grey area and maneuvering room that could allow the customer to walk away from their obligation.