For most of us a new year begin every 1/1.  But people celebrating the New Year on 1st of January represents only 40% of the World approx. 

Modern new year celebrations:

1 January: The first day of the year in the Gregorian calendar used by most countries.

Rosh Hashanah: is a Jewish celebration that occurs 163 days following Pesach, and it takes place in september.

The Eastern Orthodox Church: of Georgia, Jerusalem, Russia and Serbia still use the Julian Calendar, and the civil New Year (also celebrating the infant Jesus' circumcision) falls on 14 January.

Chinese New Year: also known as the Lunar New Year, occurs every year on the new moon of the first lunar month, around the beginning of spring (Lichun). The exact date can fall anytime between 21 January and 21 February (inclusive) of the Gregorian Calendar.

Iranian: called Norouz, is the day containing the exact moment of the vernal equinox, commencing the start of the spring season. This falls on the 20 or 21 March.

Hindu: most Hindus celebrate the New Year in early spring.

Islamic: occurs on 1 Muharram. Since the Muslim calendar is based on 12 lunar months amounting to about 354 days, the Gregorian date of this is about eleven days earlier each year.