Some ancient people had years consisting of twelve lunar months, so New Year's Day sometimes fell in the summer and sometimes in the winter. The Ancient Egyptians started their New Year at the beginning of the annual inundation, but most ancient people who had calendars based upon solar years started their New Years at (about) the time of either the vernal equinox or the winter solstice.
Today we have the start of the Jewish New Year, the Chinese New Year and the Moslem New Year, among others, all on different days.
In 18th century England the New Year started on March 25th, just after the vernal equinox. When England changed from the Julian Calendar to the Gregorian in 1752 New Year's Day was also changed to January 1st. The Tax Man wanted a full year's taxes from everyone, so it was intended that the Tax Year should go on until March 24th. But no one wanted to pay a full year's taxes for a year twelve days short and so that year, and ever since, the Tax Year went on until April 5th!
