Source and decoding - Rosh Hashanah 2a
אַרְבָּעָה רָאשֵׁי שָׁנִים הֵם, בְּאֶחָד בְּנִיסָן — רֹאשׁ הַשָּׁנָה לַמְּלָכִים וְלָרְגָלִים. בְּאֶחָד בֶּאֱלוּל — רֹאשׁ הַשָּׁנָה לְמַעְשַׂר בְּהֵמָה. רַבִּי אֶלְעָזָר וְרַבִּי שִׁמְעוֹן אוֹמְרִים: בְּאֶחָד בְּתִשְׁרִי.
There are four New Years: on 1 Nisan - for kings and festivals; on 1 Elul - for animal tithes; on 1 Tishrei - for years, Sabbatical and Jubilee years; on 1 Shevat - for trees per Beit Shammai, and Beit Hillel say on the fifteenth.
There are four New Years: on 1 Nisan - for kings and festivals; on 1 Elul - for animal tithes; on 1 Tishrei - for years, Sabbatical and Jubilee years; on 1 Shevat - for trees per Beit Shammai, and Beit Hillel say on the fifteenth. Each domain gets its own counting point.