Wikipedia:
Ancient Greeks and Romans celebrated New Year on the winter solstice [1]. However, many ancient cultures including the Phoenicians, Persians and Egyptians celebrated the New Year with the autumn equinox [2]. The ancient Romans celebrated their first New Year on January 1 in 153 BC.
During the Middle Ages under the influence of the Christian Church, many countries moved the start of the year to one of several important Christian festivals — December 25 (the Nativity of Jesus), March 1, March 25 (the Annunciation), or even Easter. Eastern European countries (most of them with populations showing allegiance to the Orthodox Church) began their numbered year on September 1 from about 988.
In England January 1 was celebrated as the New Year festival, but from the 12th century to 1752 the year in England began on March 25 (Lady Day). So, for example, the Parliamentary record records the execution of Charles I occurring in 1648 (as the year did not end until March 24), although modern histories adjust the start of the year to January 1 and record the execution as occurring in 1649.
Most western European countries changed the start of the year to January 1 before they adopted the Gregorian calendar. For example, Scotland changed the start of the Scottish New Year to January 1 in 1600. England, Ireland and the British colonies changed the start of the year to January 1 in 1752. Later that year in September, the Gregorian calendar was introduced throughout Britain and the British colonies. These two reforms were implemented by the Calendar (New Style) Act 1750.
In the 9th century, March 25 (the Feast of the Annunciation) was used in parts of southern Europe as the start of the new year. The practice became more widespread in Europe from the 11th century and in England from the late 12th century. January 1 became the official start of the year as follows:
* 1522 Venice
* 1529 Sweden
* 1544 Holy Roman Empire (Germany)
* 1556 Spain, Portugal
* 1559 Prussia, Denmark
* 1564 France
* 1576 Southern Netherlands
* 1579 Lorraine
* 1583 United Provinces of the Netherlands (northern)
* 1600 Scotland
* 1700 Russia
* 1721 Tuscany
* 1752 Britain and its colonies