The feast of the Annunciation is usually held on March 25. It is moved in the Catholic Church, Anglican and Lutheran liturgical calendars when that date falls during Holy Week or Easter Week or on a Sunday. The Eastern Orthodox Church, Oriental Orthodoxy, and Eastern Catholic Churches do not move the feast, having special combined liturgies for those years when the Annunciation coincides with another feast; in fact in these churches a Divine Liturgy is celebrated on Good Friday when it coincides with the Annunciation.
When the calendar system of Anno Domini was first introduced by Dionysius Exiguus in ad 525, he assigned the beginning of the new year to March 25 since, according to Catholic theology, the era of grace began with the Incarnation of Christ. The first certain mentions of the feast are in a canon of the 656 Council of Toledo, where it is described as celebrated throughout the church. The 692 Council of Constantinople "in Trullo" forbade observance of any festivals during Lent, excepting Sunday and the Feast of the Annunciation. An earlier origin had been claimed for it on the grounds that it appeared in manuscripts of the sermons of Athanasius and Gregory Thaumaturgus but they were subsequently discovered to be spurious.
Along with Easter, March 25 was used as the New Year’s Day in many pre-modern Christian countries. The holiday was moved to January 1 in France by Charles IX’s 1564 Edict of Roussillon. Lady Day was the English New Year’s until 1752. The change in holidays may have been the origin of April Fools’ Day. Also in England, the 1240 Synod of Worcester banned all servile work during the Feast of the Annunciation, making it a day of rest.