Michaelmas is a Christian festival observed in many Western Christian liturgical calendars on 29 September, and on 8 November in the Eastern Christian traditions. Michaelmas has been one of the four quarter days of the English and Irish financial, judicial, and academic year.

In British and Irish tradition, the quarter days were the four dates in each year on which servants were hired, school terms started, and rents were due. They fell on four religious festivals roughly three months apart and close to the two solstices and two equinoxes.