Calendar quarter
Calendar quarter means a 3-month period within a calendar year. The first calendar quarter begins on January 1 of the calendar year and ends on the last day of March. The second calendar quarter begins on the first day of April and ends on the last day of June. The third calendar quarter begins on the first day of July and ends on the last day of September. The fourth calendar quarter begins on the first day of October and ends on the last day of December.