Different cultures celebrate New Years on different days depending on the calendar that they are using. For the vast majority of the world that day is January 1st. This day was chosen to be used on the Gregorian Calendar due to the preceding calendars the Old Roman Calendar and the Julian Calendar both had New Years on that day.
The Costumer has a wide range of costumes and accessories for celebrating the New Year including party kits, father time wigs and beards, and baby costumes for Baby New Years.