Hacham Ovadia Yosef ZT"L rules that when Yom Kippur falls on Shabbat, the Kabbalat Shabbat service is not recited on Friday night, the night of Yom Kippur. In such a case, he writes, we do not recite Mizmor Le'David or Lecha Dodi, and we instead begin the service with "Mizmor Shir Le'yom Ha'Shabbat" and then proceed directly to the hymn "Lecha Keli Teshukati." This is based on the position of the Kanhag ("Kenesset Ha'gedola" – Rabbi Haim Banbenishti, Turkey, 1603-1673), who writes that we do not receive a "Neshama Yetera" ("extra soul") when Shabbat falls on Yom Kippur, as we do on an ordinary Shabbat. Since we do not eat meals when Shabbat falls on Yom Kippur, we are not endowed with a "Neshama Yetera." (This is also the reason why we do not recite a Beracha on Besamim after Yom Kippur even when it falls on Shabbat.) The Kanhag thus writes that according to Kabbalistic teaching, we do not recite Kabbalat Shabbat on the eve of Shabbat Yom Kippur. From the Gemara, however, it appears that there is no difference between Shabbat Yom Kippur and ordinary Shabbatot with respect to Kabbalat Shabbat. Therefore, Hacham Ovadia Yosef follows the position that we omit most of Kabbalat Shabbat but recite "Mizmor Shir Le'yom Ha'Shabbat," to satisfy all views. However, the custom of our community does not follow Hacham Ovadia's ruling in this regard. As written in our Mahzorim, we follow the custom to recite the ordinary Kabbalat Shabbat on the eve of Shabbat Yom Kippur. The only exception is that we obviously omit the recitation of "Bameh Madlikin." Thus, according to our custom, the procedure for the Yom Kippur eve prayers when it falls on Friday night is as follows: Mizmor Le'David, Lecha Dodi, Mizmor Shir, Kol Yisrael, Rabbi Hananya, and Lecha Keli, followed by the standard Yom Kippur service. It should be noted that "Lecha Keli," with which we begin the Yom Kippur service, is an especially significant prayer. Some say it was authored by Rabbi Abraham Ibn Ezra (Spain, 1089-1164), whereas others claim that it was written by his contemporary, Rabbi Yehuda Halevi. The hymn is a confession of sin, and it is recited as the sun sets on the eve of Yom Kippur in order to ensure that we have no opportunity to sin between or confession on Ereb Yom Kippur and the onset of Yom Kippur itself. (In fact, some claim that it was originally written as a deathbed confession to be recited in the final moments of one's life.) This is not a song that we sing for inspiration, or simply to feel joyous and uplifted, but rather a very significant prayer that must be recited with seriousness and concentration. When Yom Kippur eve falls on Friday night, we recite after the Amida prayer in Arbit "Vayechulu" and the Me'en Sheba blessing. The Hazzan must ensure to recite "Ha'Melech Ha'kadosh She'en Kamohu," as opposed to the usual text of "Ha'Kel Ha'kadosh She'en Kamohu." There is considerable discussion and debate among the Poskim concerning the case where a Hazan mistakenly recited "Ha'Kel Ha'kadosh" and completed the Beracha before his mistake was noticed. Hacham Ovadia Yosef rules that since this issue is subject to debate, the Hazan does not repeat the Beracha in such a situation. Clearly, however, care must be taken to recite the Beracha properly and to avoid this question. Summary: Different customs exist concerning the Kabbalat Shabbat service on the night of Yom Kippur that falls on Shabbat. The custom in our community is to recite the full Kabbalat Shabbat service as we do every Friday night, omitting only "Bameh Madlikin." When Yom Kippur falls on Shabbat, we recite after the Amida of Arbit "Vayechulu" and "Me'en Sheba." The Hazzan must remember to recite "Ha'Melech Ha'kadosh She'en Kamohu," as opposed to the usual text of "Ha'Kel Ha'kadosh She'en Kamohu." If he mistakenly recited "Ha'Kel Ha'kadosh," he does not repeat the Beracha.