Halocho #736 - Bat/Bar Mitzvas in a Jewish leap year

This year is a Jewish leap year; the 12th month (starting on Shabbat) will be Adar-I (or "Adar-Alef" or "Adar-Rishon") and the 13th month will be Adar-II (or "Adar-Bet" or "Adar-Sheni").

Girls and boys born in Adar (12 and 13 years ago) do not become Bat/Bar Mitzva until Adar II.

Girls born in either Adar-I or Adar-II this year will become Bat Mitzva in Adar, in 12 years time.

In 13 years time will again be a leap year, so boys born in either Adar-I or Adar-II this year will be Bar Mitzva on their "real" birthday.

Source: Kitzur Shulchan Aruch 15:2

- Danny
Monday, 26 Shvat 5771

Halocho #278 - When the younger becomes Bat Mitzva first

12 years ago - 5757 - was a leap year on the Jewish calendar; the month of Adar was doubled. This year is not a leap year. Girls born 12 years ago in both Adar-I and Adar-II become Bat Mitzva on the same date this year in Adar. For example, a girl born 12 years ago on the 28th Adar-I will become Bat Mitzva in 4 weeks time, four weeks after her friend who was born 3 days later than her - on 1 Adar-II - who became Bat Mitzva today. Source: Kitzur Shulchan Aruch 15:2 Chodesh Tov! - Danny Wednesday, 1 Adar 5769 Please daven for a complete recovery for Tamar bat Naama - תמר בת נעמה