Like most of Marriott's other rates, the reward redemption rate I booked recently lists "1 NTS RM & TX CXL PENALTY -AS FIRST NIGHT PAYMENT" as a penalty for no-shows who don't cancel by 18:00 on the day of arrival. I'm a good traveler and I always cancel hotel reservations I don't plan on using , but I still have this nagging question: How is room and tax for one night calculated on a free stay?