When May One Pay Back More Than They orrowed?
If a person bought an aliyah in shul and committed to pay by a certain date, he may not arrange for the payment date to be postponed in exchange for increasing his donation, since that would constitute ribbis ketzutzah (interest set in advance). If one borrows money from a pushka (a charity box) or from someone who is collecting money (either for for a moisad, an institution, or for poor people), it’s permissible to give back more money than they borrowed; the additional money is considered tzedakah (charity) and is not considered ribbis me’ucheres (late interest)—as long as they had not resolved at the time they borrowed the money to give back more. However, if the money is being collected for one specific ani (poor person) it is already considered as belonging to the ani, and one may not put back into the pushka—or repay the collector—more than they originally borrowed, since it would be considered ribbis me’ucheres. If a person borrowed money from another, but is not sure of the amount and therefore wants to pay back a sum that may exceed the amount they borrowed, they may do so lehotzie misafek (in order to eliminate any doubt)—but it must be limited to the maximum amount they may have borrowed. #400