A year is made up of a given number of months, and not a given number of days: Megillah 5a
A month is made up of a given number of days, and not a given number of hours: Rosh HaShanah 5a; Megillah 5a
Tishrei
Tishrei is also known as the month of the "Eitanim [Strong Ones]": Rosh HaShanah 11a
Tishrei as the official beginning of the Cycle of Seasons: Rosh HaShanah 8a
Whether the world was created in the month of Nisan, or the month of Tishrei: Rosh HaShanah 8a, 10b, 11a, 27a
Tishrei as the month of Judgment for the world's population: Rosh HaShanah 8a-b, 34a
Whether the ultimate redemption will be in Nisan or Tishrei: Rosh HaShanah 11a
The first of Tishrei as the potential demarcation of the New Year for bringing animals for the Tithing of Animals: Rosh HaShanah 2a, 7b
The first of Tishrei marks the New Year for numbering the years of a non-Jewish King on a legal document: Rosh HaShanah 2a-4a, 8a
The first of Tishrei is the demarcation for the beginning of the Sabbatical Year: Rosh HaShanah 2a, 8b
Whether the 1st or 10th of Tishrei marks the beginning of the Jubilee Year: Rosh HaShanah 2a, 7b, 8b
The first of Tishrei is the demarcation of the beginning of the year in counting for the prohibition against use of the First 3 Years of a tree's Produce: Rosh HaShanah 2a, 9b
The first of Tishrei is the demarcation between years in Tithing Vegetables: Rosh HaShanah 2a, 12a
The first of Tishrei is the demarcation between years in Tithing Grain: Rosh HaShanah 8a, 12a
Whether Abraham and Jacob were born in Tishrei or Nisan: Rosh HaShanah 10b, 11a
The verdict condemning the Generation of the Flood was set in the Month of Tishrei: Rosh HaShanah 12a
Cheshvan
Use of the term "Marcheshvan [lit. "Bitter Cheshvan", although there are other sources for the phrase]": Rosh HaShanah 7a, 11b
Whether the Flood began on the 17th of Cheshvan or of Iyyar: Rosh HaShanah 11b-12a
Either the 1st or 15th of Shevat is the demarcation date between years for separating Terumah on a tree's fruit from year to year: Rosh HaShanah 2a, 14a
Adar
We increase happiness in Adar: Taanit 29a-b
One who has a court appearance against someone who isn't Jewish [and hence doesn't share the special "luck" of Adar] should postpone it until Adar: Taanit 29b
On the first of Adar, the announcement to watch out for newly grown mixed-species was made: Megillah 13b, 29b
On the first of Adar, the announcement to prepare the Shekel-Donations for the Temple was made: Megillah 13b, 29a-b
On the 15th of Adar, special money-changers were established to aid acquisition of the Half-Shekel for its donation to the Temple: Megillah 29b
On the 25th of Adar, special money-changers were established in the Temple itself to aid acquisition of the Half-Shekel for its donation to the Temple: Megillah 29b
Celebration of the 28th of Adar as a holiday: Rosh HaShanah 19a
Nisan
Nisan is also known as the month of "Ziv [Beauty]": Rosh HaShanah 11a
Nisan as the first of the months: Rosh HaShanah 2a, 7a
Nisan as the month symbolizing redemption: Megillah 6b
Whether the world was created in the month of Nisan, or the month of Tishrei: Rosh HaShanah 8a, 10b, 11a, 27a
The 1st of Nisan is the beginning of the year in numbering the years of a Jewish King on a legal document: Rosh HaShanah 2a, 2a-3a, 8b
The 1st of Nisan is the beginning of the year in counting for the Prohibition against Delaying the fulfillment of vows: Rosh HaShanah 2a, 4a-b, 6b, 7b
The 1st of Nisan is the beginning of use of the new Half-Shekel Donations to the Temple: Rosh HaShanah 7a; Megillah 29b
Whether Abraham and Jacob were born in Tishrei or Nisan: Rosh HaShanah 10b, 11a
How to figure out that the Jews left Egypt in Nisan: Rosh HaShanah 2b-3a, 11a, 11b
The 16th of Nisan is the date when New Produce becomes permitted: Rosh HaShanah 7b
Isaac was born on Passover: Rosh HaShanah 10b, 11a
Whether the ultimate redemption will be in Nisan or Tishrei: Rosh HaShanah 11a Haman was sent to Mordechai to reward him on the 16th of Nisan: Rashi Megillah 16a "UleTa'anito" Miriam died in this month: Taanit 9a
Iyyar
Whether the Flood began on the 17th of Cheshvan or of Iyyar: Rosh HaShanah 11b-12a
Sivan
The 6th of Sivan is when the New Flour is permitted for use in Temple Offerings: Rosh HaShanah 7b
Av
We minimize happiness in the month of Av: Taanit 29a-b Aharon died on the first of Av: Rosh HaShanah 2b
Elul
The first of Elul as the potential demarcation of the New Year for bringing animals for the Tithing of Animals: Rosh HaShanah 2a, 7b, 8a
Whether Elul can have an extra day added to it: Beitzah 6a; Rosh HaShanah 19b, 32a