Dear Yisroel,

We are "Moser Moda'a" in our Hataras Nedarim every year because of the Gemara (Nedarim 23b) that says: "Someone who desires that his Nedarim should not go into effect that year should stand up on Rosh Hashanah [and be Moser Moda'a]." The Gemara seems to be saying that one should be Moser Moda'a every Rosh Hashanah. Your question is, why? If we put no time limit on the Mesiras Moda'a, then why isn't once enough? Here are two possible answers:

1. Some Poskim maintain that if one makes a Neder knowing full well that earlier he had been Moser Moda'a, then his Mesiras Moda'a is not only overridden regarding the Neder that he is making now but is completely nullified regarding future Nedarim (see Chachmas Adam 94:6). In that case, we can understand why it is advisable to make a new a Mesiras Moda'a every year; perhaps the person inadvertently nullified his Mesirah from last year and any Nedarim he makes now will go into effect.

2. At Kol Nidrei, we are also Moser Moda'a. However, unlike on Erev Rosh Hashanah, we say "from this Yom Kippur until the next." Rav Shlomo Zalman Auerbach zt'l writes (see Minchas Shlomo, Nedarim 23b) regarding Kol Nidrei that the Chachamim wanted to incorporate into the Nusach ha'Tefilah a Mesiras Moda'a for the benefit of those that did not make one in previous years and they stipulated that it should be for just one year, because it would be degrading (Zilzul) to the Mesiras Moda'a to make it each year for all time. On Erev Rosh Hashanah, when we do not say the Mesiras Moda'a in front of the Tzibur, there is no concern of Zilzul, and so we make it for all time. Accordingly, once indeed is enough, but it was incorporated into the standard Nusach of Hataras Nedarim for the benefit of those who had never said it before.

Kol Tuv,

Yonasan Sigler

This is not a Psak Halachah