The Mishnah lists **four** different “new years.”
This teaching appears at the beginning of Mishnah Rosh Hashanah. The four dates mark separate beginnings for different legal, agricultural, and religious calculations rather than four competing celebrations of the same civil year.
The first is the first of Nisan, which begins the year for kings and the cycle of the pilgrimage festivals. The first of Elul was associated with tithing animals, although later halakhic practice generally treats that calculation as tied to Rosh Hashanah. The first of Tishrei, Rosh Hashanah, begins the ordinary calendar year and determines sabbatical and Jubilee-year reckoning. The fifteenth of Shevat, Tu BiShvat, serves as the new year for trees, especially in matters involving tithes and the age of fruit trees.
The number can seem surprising because modern usage usually treats “New Year” as one date. In the Mishnah, however, a new year means the starting point for a particular system of counting. The list is therefore four, not five or three. The tractate’s opening discussion is a calendar framework for Jewish law, not simply a list of holiday names.