Book of Common Prayer (page 15)

The Calendar
of the Church Year

The Church Year consists of two cycles of feasts and holy days: one is
dependent upon the movable date of the Sunday of the Resurrection or
Easter Day; the other, upon the fixed date of December 25, the Feast of
our Lord's Nativity or Christmas Day.

Easter Day is always the first Sunday after the full moon that falls on
or after March 21. It cannot occur before March 22 or after April 25.

The sequence of all Sundays of the Church Year depends upon the date of
Easter Day. But the Sundays of Advent are always the four Sundays
before Christmas Day, whether it occurs on a Sunday or a weekday. The
date of Easter also determines the beginning of Lent on Ash Wednesday,
and the feast of the Ascension on a Thursday forty days after Easter
Day.

1. Principal Feasts

The Principal Feasts observed in this Church are the following:

Easter Day

Ascension Day

The Day of Pentecost

Trinity Sunday

All Saint's Day : November 1

Christmas Day : December 25

The Epiphany : January 6

These feasts take precedence of any other day or observance. All
Saints' Day may always be observed on the Sunday following November 1,
in addition to its observance on the fixed date.