Rav Moshe Speter , Former Rosh Kollel, Washington Kollel, Torah Mitzion
The month of Adar I is added to the calendar during a shana me’uberet (a leap year).
The Mishna (BT Megillah 6b) states:
“There is no difference between the first Adar and the second Adar – except for reading the Megillah and matanot li’evyonim(gifts to the poor).”
Based on the Gemara, we consider both Adars as equivalent in terms of the issur (prohibition) of eulogies and fasting on the days of Purim (i.e. the 14th and 15th of both months). On these days, we do not say tachanun, lamnatzeach… ya’ancha Hashem, or tzidkatcha (on Shabbat). Some authorities rule that one should feast and rejoice on the two days of PurimKatan. The Rama concludes:
“In any event, he should indulge a bit in feasting, in order to accommodate those who are stringent…”
Bar Mitzvah: If a boy was born during a regular year, he does not become a bar mitzvah until Adar II (assuming that the bar mitzvah occurs during a shana me’uberet).
An interesting case involves twins who were born on Rosh Chodesh Adar II – where the elder was born on 30 Adar I, and the younger was born several minutes into 1 Adar II – but their bar mitzvah occurs during a regular year. In such a situation, the younger one celebrates his bar mitzvah first – on Rosh Chodesh Adar. Meanwhile, the elder twin must wait a full twenty-nine days – until Rosh Chodesh Nissan – for his own bar mitzvah.
Yahrzeit: The poskim disagree when it comes to the yahrzeit of someone who was born during a regular year: Should the yahrzeit be commemorated during Adar I or Adar II? According to the Shulchan Aruch, the yom hazikaron (yahrzeit) comes out during Adar II, but Ashkenazim commemorate the yahrzeit during Adar I.
Commemorating a miracle:
“One who benefited from a miracle during Adar and accepted upon himself an annual day of feasting and rejoicing – if [the miracle] occurred during a simple (i.e. regular) year, he holds [the anniversary] during the first [Adar]. And if [the miracle] occurred during a me’uberet in the second [Adar], he should hold [the anniversary] during the second [Adar]. And that festive meal – which is held to commemorate the miracle – is a seudat mitzvah, because every festive meal which is held to commemorate the wonders of Hashem is a seudat mitzvah.”