Cash plus points splits the price of a reward between currency and money. The program sets the conversion, defining how many points offset each unit of cash and any floor or ceiling on the points portion. At redemption, the member chooses a mix, the system deducts the points and charges the remaining cash, and fulfillment proceeds as with any redemption.
Consider a member who wants a reward flight but is a few thousand miles short. Rather than wait or abandon the booking, the member covers the gap with cash. The redemption happens now instead of later or never, the member gets the trip, and the program draws down part of the outstanding balance it would otherwise carry.
For an enterprise operator, cash plus points widens the redeeming population beyond members with full balances, which lifts redemption and engagement while bringing in incremental cash. It also gives finance a way to move liability off the books steadily. The design work is setting the cash-to-points ratio so the option is attractive to members without underpricing the currency.