My mother passed away in the month of Adar of 5756 (1996). When do I observe the yahrtzeit on this year, a leap year that has two Adars?
Most years on the Jewish calendar (almost two thirds of them) have only one Adar. On a leap year, however, there are two Adars. (See Years for more information on how the leap year system works.) So which of the leap year's two Adars correspond to the Adar of the regular year?
The Talmud discusses a similar question: If one is drawing up a document during Adar of a leap year, how should it be dated? Rabbi Meir says that in Adar I we write "Adar I" but during Adar II, we write "Adar" – un-appended – because when the word Adar is unqualified, it means Adar II. Rabbi Judah says exactly the opposite: "Adar" on its own means Adar I; when referring to Adar II, one must specifically write "Adar II."
Maimonides rules according to Rabbi Meir's view—that the main Adar is Adar II. Thus, it would make sense to observe the yahrtzeit during Adar II. However, there is also reason to argue that one should observe the yahrtzeit on Adar I, based on the halachic rule that requires a person to always do a mitzvah at the first possible opportunity. According to this principle, the yahrtzeit – and its associated mitzvot – should be observed in the first Adar.
So practically what is one to do? Different communities have different customs. In some communities the yahrtzeit is observed in Adar I and in others, Adar II. Yet others observe the yahrtzeit in both Adars. Speak to your rabbi to find out what your community's custom is.
Rabbi Eliezer Posner