My part timers pay daily. The arrangements I have had previously were "guaranteed" part time. This meant that they paid me a minimum, agreed upon amount at the beginning of the month. For example, they need at least 6 days of care, they pay for at least 6 days every single month, on the first. Should they request a STAT day as one of those days, I would let them know that I am closed, and that they can choose another day during the month if they wish. If they don't (and they always do) then yes, they would still pay the flat fee that month.