In the US, New Years Day is January first. In other parts of the world, the new year is based on the lunar calendar. But in many parts of the world, the celebration of the new year was connected to the religious calendar. In fact, until the year 1752 (when the Julian calendar was adopted), the new year was observed on “Lady Day,” or March 25th, the feast of the Annunciation.
It doesn’t take much calculation to realize that March 25th is precisely nine months before the celebration of Christmas. It also follows the vernal equinox, just as Christmas follows the winter solstice. So the coming of Spring, with it’s evidence of new life, is a natural time for the observance of a new year, and for marking the angel Gabriel’s announcement to the Virgin Mary that she would conceive and bear the Savior.
The first authentic reference to the feast of the annunciation are in a canon of the council of Toledo (656), and another from the council of Constantinople (in 692), forbidding the celebration of all festivals in Lent, excepting the Lord’s day and the Feast of the Annunciation. A synod held at Worcester, England (1240), forbade all servile work on this feast day.
For Catholics, the theological importance of the Annunciation is it’s marking of the beginning of the fulfillment of God’s promises and preparations (CCC 484). Mary’s assent to the angel’s announcement was the beginning of Christ’s Incarnation; God’s coming into the world a fully human, born as we are born, with a grace-filled human mother. Although the feast of the Assumption is no longer the beginning of our year, we remember each year that it was the beginning of Christ’s coming for our salvation.