If somebody hires a Jewish worker to perform a given service, may he ask for a discount in exchange for prepaying, or does this violate the prohibition of Ri’bitt (interest)? For example, if a person wishes to hire a Jewish painter for a job worth $1500, may he pay $1000 up front and then be exempt from the remaining $500?
The Rambam (Rabbi Moshe Maimonides, Spain-Egypt, 1135-1204), in Hilchot Malveh Ve'loveh (7:12), addresses this case and rules that the permissibility of such an arrangement depends on whether or not the worker begins working immediately after receiving payment. If the worker begins his service immediately after receiving payment, then this arrangement does not violate the prohibition of Ri’bitt; the worker is entitled to accept a lower fee for his service, and this is not seen as a situation of interest. If, however, the worker receives full payment up front and after a period of time provides service valued at a higher price, then this arrangement is indeed forbidden. In this case, the Rambam rules, the worker's receipt of payment outwardly resembles a loan, and thus the extra service performed gives the appearance of Ri’bitt. Since he does not begin working immediately, it appears as though he received a loan which he repays through the services rendered. And since the value of those services exceeds the amount of money he had received, this arrangement resembles Ri’bitt. When, however, he begins working immediately, it is clear that he received the money as payment for his services, and not as a loan. (See Rabbi Moshe HaLevi’s "Milveh Hashem," page 79)
If a worker does not begin working immediately after receiving payment, he may still perform the service at a discounted rate if he and the client make a "Kinyan" – a formal, symbolic act of agreement, such as a handshake or transfer of a handkerchief. If they make a Kinyan when the money is paid, the worker can not back out on the commitment to do the job and it would be considered as if he started.
A similar question arose regarding the Israeli bus companies that sell tickets that can be used for a certain number of rides. Normally, the tickets that are sold offer one more bus ride than the ticket's price would otherwise buy. Thus, by paying up front, the customer receives services of a higher value than the sum he paid. Halacha permits this arrangement because the passenger receives a ticket immediately upon paying the money. Since he receives a ticket, it is clear that he has purchased something at a discount, and has not lent money upon which he receives interest. "Milveh Hashem," page 80)
Summary: A Jewish worker may provide service at a discounted price in exchange for prepayment only if he begins working immediately upon receiving the payment, or if he and the client make a symbolic "Kinyan" – such as a handshake – when the payment is rendered. It is permissible for bus companies to sell tickets worth more bus rides than the price of the ticket would otherwise be able to buy.
