Traditional factoring is based in a whole turnover assignment of debt: all clients invoices best in the factor as soon as they are created. Single invoice factoring uses a facultative assignment, where the factor is not obliged to purchase the clients debt. This is sometimes called ‘offer and acceptance’. The key advantage to the factor of whole turnover assignment is that all debts belong to the factor whether uploaded to their system or not. The client may be required to repurchase debts such as those disputed or subject to set off.  The advantages to the factor for facultative assignment are limited.