The anniversary of the date of passing is very significant in Judaism. Kabbalah teaches that all the spiritual achievements of one's life, including every positive thought, word, or deed, radiate and are revealed in the world and in the Heavens on that day.
On the Yartzeit (Yid. "anniversary"), the soul is at its greatest strength and in its fullest glory. With each ensuing year, this radiance again shines forth in the world and in the Heavens, as the soul is elevated to a higher spiritual level and drawn even closer to G‑d.
While the spiritual radiance from above can influence those below, children of the deceased (as well as students, friends, relatives, even strangers) can similarly benefit those above. On this day, every mitzva performed and every effort to improve one's spiritual life brings great merit to the deceased. This is especially true for one's father and mother.
A Deeper Perspective
A Yartzeit is generally associated with two mixed feelings. On one hand, we learn from our sages that the soul of the departed rises from one spiritual world to a higher one. This is, therefore, a day of rejoicing for the soul, hence a day of corresponding joy for the near and dear ones left behind. On the other hand, the Yartzeit naturally emphasizes the loss sustained by the family, which results in a feeling of sadness. In truth, however, the Yartzeit should not call forth feelings of sadness, but rather a feeling of reflection, self-examination, and repentance.
During this day, one should work to align one's life on this earth to the path followed by the soul above, which is constantly on the ascent. This is to say, just as the soul continuously rises year after year, going from strength to strength, so must those associated with the soul steadily rise in their advancement in Torah knowledge and observance of mitzvot. By doing so, they give the soul of the departed the greatest possible joy.
This approach underlines the basic view of Judaism that, in reality, there is no "death" in matters of G‑dliness. Rather, the Yartzeit, and even the very day of passing, represents a transition. But this transition is unique for it goes in only one direction — higher and higher, from strength to strength — first in this world, and later in the following world.
Calculating the Date of the Yartzeit
The date of the Yartzeit follows the Jewish calendar, and is generally calculated from the time of passing, not the time of burial. For example, if the person passed away on the twenty-fourth day of Av, the Yartzeit is observed each year on the twenty-fourth day of Av. Some calculate the date of the second (and every future) Yartzeit from the date of burial. One should follow the custom of his community, or ask a competent rabbi for guidance.
If the time of passing was during the twilight (either between sunset and dusk, or between dawn and sunrise), one should consult a competent rabbi, since Jewish law determines dates from sunset to sunrise (i.e. Monday night is considered to begin Tuesday's date).
According to the Jewish calendar, the months of Cheshvan and Kislev sometimes have twenty-nine days and sometimes thirty days. If the passing occurred on the thirtieth day of either of these months, consult a competent rabbi to ascertain the correct date to observe the Yartzeit.
The same applies in leap years. According to the Jewish calendar, leap years have two months of Adar. If the passing occurred during Adar in a regular year, or if the passing occurred on the first day of Rosh Chodesh or during "Adar II," consult a competent rabbi to ascertain the correct date to observe the Yartzeit.
If one does not know the date of passing (and cannot find out), he should consult a competent rabbi and designate a day on the Jewish calendar to be observed every year as the Yartzeit.
Some Yartzeit Customs
It is customary for men to arrange to be called up to bless the Torah during the Shabbat services of the week prior to the Yartzeit, and to recite the Half-Kaddish after the Torah reading. Some arrange to read the Maftir (special portion recited after the Torah reading) as well.
If the Yartzeit is on a Monday or Thursday, men should arrange to be called up to bless the Torah during the services, and to recite the Half-Kaddish after the Torah reading.
On the eve of the Yartzeit, each mourner kindles a candle that should remain lit for the entire twenty-four hour period.
Some take upon themselves to fast on the day of the Yartzeit (beginning at dawn) in order to be aroused to repentance and self-examination. If one is fasting, he adds the "Anaeinu" portion in the Amidah (silent prayer) when praying on the day of the Yartzeit. One may not fast on days when Tachnun is not recited, as well as on the day of one's son's Brit Milah (circumcision of a child) or Pidyon Haben (redemption of the firstborn son). Also, a bride and groom may not fast during the week following his wedding.
If possible, a man observing a Yartzeit should lead all the prayer services of the Yartzeit day (Maariv , Shacharit , and Mincha). If one does not lead the services, one should at least pray with a Minyan (quorum of ten Jewish males over age thirteen) and recite the Mourner's Kaddish at the designated times during the service.
One kindles five candles on the prayer leader's stand in the synagogue when leading the prayer services.
Some put out cake, schnapps or whiskey after the morning service. Those present say L'Chayim, and state a wish that "the soul should be elevated in the heavenly spheres."
Many study Mishnayot (Mishna laws) in honor of the soul, especially the chapters that begin with the letters of the Hebrew name of the departed. They also study the chapters that begin with the letters of the word Neshama (soul).
Some visit the gravesite on this day to recite prayers and Psalms. Some people recite Psalms, including Psalm 91, and some add Psalms 33, 16, 17, 72, 104, and 130. Some also recite verses from Psalm 119 that begin with the letters of the Hebrew name of the deceased, and the word נשמה (Heb. soul). Some recite additional prayers and supplications.