Kol Nidrei-Conditioning ones future vows:[1]

Is not an annulment but rather a stipulation:[2] Kol Nidrei is not the annulment of one’s previous vows, but rather is a stipulation on one’s future vows, that if one makes a vow in the future, it should be nullified. [In Hataras Nedarim that is said on Erev Rosh Hashanah, however, we do both; we nullify the previous vows and stipulate the future vows.]

Is said before sunset in the presence of three:[3] The custom is to begin saying Kol Nidrei while still day [before sunset] and in the presence of another two people who stand beside the Chazan.[4] 

Removing three Sifrei Torah:[5] Three Sifrei Torah are removed from the Ark prior to Kol Nidrei. 

Saying Kol Nidrei together with the chazzan: The congregation is to recite Kol Nidrei quietly together with the Chazan.[6] It should be said, by each congregant, loud enough for the people around him to hear.[7] 

Is repeated three times with raising of voice:[8] Kol Nidrei is repeated three times, with the Chazan raising his voice louder each time it is said.[9]

Saying it with a melody until night:[10] Kol Nidrei is to be said with a melody and drawn out until nighttime.[11] The chazzan should only sing melodies that the congregation is accustomed to, in order not to confuse them.[12]

Q&A

Are women to also say Kol Nidrei quietly together with the Chazan?

Yes.[13]

Are all one’s future vows invalidated due to the stipulation made by Hataras Nedarim?[14]

This depends on whether one remembered his stipulation at the time of the vow. If one remembered the stipulation made, at the time that he said the vow, then the vow is binding and not considered annulled.[15] Furthermore, all future vows from that point and on are considered valid even if he did not remember the stipulation.[16] If, however, at the time of saying the vow one did not remember the stipulation, then in such a case it is considered null and void.[17] Nevertheless, one may only rely on this stipulation to invalidate his vow in a pressing situation. In a non-pressing situation, one must seek a Beis Din to annul the vow.[18]

Chumras and customs: Some opinions[19] rule that those vows which came as a result of following a Chumra or Hiddur Mitzvah, such as one who performed a Hiddur three times, then the stipulation made during Hataras Nedarim is valid to uproot the status of vow from the Hiddur, even if it does not involve a time of need. [This however only applies if one did not remember the stipulation at the time of performing the Mitzvah. If, however, he remembered the stipulation and disregarding it performed the Mitzvah without saying Bli Neder, the Mitzvah receives the status of a vow.[20]]

_______________________________

^[1] Admur 619/2-5; Rama Yoreh Deah 211/1; See Piskeiy Teshuvos 619/1

[2] Admur 619/4

Why does one need to say a Modah on his vows twice, by Hataras Nedarim and by Kol Nidrei? The Tur 619 writes that the custom is to recite the stipulation on Erev Yom Kippur. The Shlah ibid writes that “Zrizin Makdimim Lemitzvos” and they hence precede the stipulation to Erev Rosh Hashanah. Some say the reason for this is because we suspect that perhaps one will not fulfill his obligation with the stipulation said on Erev Yom Kippur being that it requires another three people to hear him and that he thus must say it aloud to himself, which may not be fulfilled. [Minchas Yitzchak ibid]

[3] Admur 619/4

[4] The reason: As since stipulating future vows is similar to annulment of previous vows, therefore, the custom is to begin saying it before night and for the chazzan to say it in the presence of another two people which stand beside him, which is required by annulment of vows. This is done in order to prevent people from mistakenly thinking that annulment of vows may be done on Shabbos [as only vows which have a Shabbos need may be annulled on Shabbos], and that it does not need to be done in front of three people. [Admur ibid]

^[5] Alef Lamateh 619/15 in name of Peri Eitz Chaim and Shiyurei Kneses Hagedola; Shevach Hamoadim p. 45

[6] The reason: As the stipulation made by the Chazan is not effective for anyone else other than himself. It is for this reason that the wording of the stipulation is in singular form.

[7] See Shach Yoreh Deah 211/2

[8] Admur 619/5

[9] The reason: This is done in order to instill awe and fear into the listeners. [Admur ibid]

[10] Admur 619/5

[11] The reason: This is done in order to Daven the evening prayer at its proper time [and not beforehand]. [Admur ibid]

[12] Admur 619/6

[13] See Minchas Yitzchak 9/61

[14] Yoreh Deah 211/2; Alef Hamagen 581/102; M”B 619/2; Piskeiy Teshuvos 581/17

[15] Michaber 211/2

[16] Alef Hamagen 581/102

[17] Michaber ibid; The Michaber ibid however brings an opinion [opinion in Rambam Nedarim 2] who rules the vow is only invalidated due to the stipulation if one remembered the stipulation after making the vow, within the amount of time of Kdei Dibbur, and he explicitly thought in his mind to rely on the stipulation. The Michaber concludes that one is to suspect for this opinion. The Taz 211/3 however argues that according to all the stipulation is valid even if one remembers it much later on, after he made the vow, so long as he decides to validate the stipulation within Kdei Dibbur of remembering it. The Nekudos Hakesef however argues on the Taz and defends the understanding and ruling of the Michaber in the Rambam. See Birkeiy Yosef 228/2 who brings from the Shut of the Beis Yosef Avkas Rochel 176 that he does not suspect for the words of the Rambam at all. However here in his Shulchan Aruch he suspects for his opinion.

[18] Rama 211/1

[19] Salmas Chaim 467; Minchas Shlomo 91/20; Yabia Omer 2/30

[20] Piskeiy Teshuvos 581 footnote 111