The period of time a casino considers a single gaming day. Typically, the Slot Day day differs from the normal day and typically begins early in the morning rather than at midnight (perhaps to correspond with a shift change). The Slot Day is used (not the date) for comp rating purposes. At many casinos, the date on the W2-G is also based on the Slot Day, so that a jackpot won just after midnight on New Years is reported for "last year"