Lighting Candles and Kiddush on Yom Kippur that Falls on Shabbat

Shalom Rav,

1. When Yom Kippur falls on a weekday, one should light candles on the eve of Yom Kippur and recite the blessing:

"Blessed are You, Hashem, our God, King of the Universe, who has sanctified us with His commandments and commanded us to light a candle for Yom Kippur" 

"ברוך אתה ה' אלוקינו מלך העולם אשר קדשנו במצוותיו וציוונו להדליק נר של יום הכיפורים"

(see Shulchan Aruch, Orach Chaim, Siman 618, Sections 1-2, Mishnah Berurah there, and Responsa Yechaveh Da'at, part 3, Siman 40, and Chazon Ovadia, Yamim Nora'im, page 270). However, for those who follow the rulings of the Gra, one should not recite a blessing when lighting the Yom Kippur candle; see the commentary of the Gra there, Section 2, and Maaseh Rav, Siman 241).

In the year that Yom Kippur falls on Shabbat, the lighting of the candles serves both for Shabbat and for Yom Kippur, and one should recite the blessing: 

"Blessed are You, Hashem, our God, King of the Universe, who has sanctified us with His commandments and commanded us to light a candle for Shabbat and for Yom Kippur"

"ברוך אתה ה' אלוקינו מלך העולם אשר קדשנו במצוותיו וציוונו להדליק נר של שבת ושל יום הכיפורים"

(Rema there, Section 1).

2. One does not perform the regular Kiddush on Yom Kippur that falls on Shabbat. However, one should intend to fulfill the obligation of Kiddush during the Shemoneh Esrei prayer at night, with the blessing that concludes with "who sanctifies the Shabbat, Israel, and Yom Kippur." It is good for the chazzan to announce before the evening prayer that the entire congregation should have this intention in order to fulfill the obligation of Kiddush (Chazon Ovadia there, page 84; thus wrote in Responsa Zikhron Yehudah, part 2, end of Siman 268, and in Responsa Har Tzvi, part 1, section Orach Chaim, Siman 130, in the name of the gaon Rabbi Avraham Shaag, author of Ohel Avraham).

Blessings,

Hillel Meirs