As mentioned above, (in Ashkenazi communities) outside Israel, the Kohanim administer the Birkat Kohanim on holidays only, during the Musaf prayer. In Israel, too, only in Jerusalem is the Birkat Kohanim performed every day. The rest of the country suffices with a weekly blessing administered on Shabbat.

(The Rebbe points out that the Land of Israel is the "heart" of the globe; the conduit through which the entire world receives its Divine flow of energy. Similarly, the daily blessings issued by the Kohanim in Jerusalem extend throughout the entire world, showering G‑d's blessings on Jews in the rest of the Land and the Diaspora as well.)

During those prayers which are essentially eligible for the Birkat Kohanim – i.e. Shacharit of every day, and Musaf of Shabbat, Chol Hamoed and Rosh Chodesh – while Birkat Kohanim is not performed, the chazzan recites the following short prayer, in lieu of the Birkat Kohanim, during the Repetition of the Amidah, immediately before the Sim Shalom blessing:

"Our G‑d and G‑d of our fathers, bless us with the threefold blessing written in the Torah by Moses Your servant, and pronounced by Aaron and his sons the Kohanim… [and the prayer concludes with the text of the Priestly Blessing]."

In Chabad congregations, when the chazzan concludes each of the three verses of the blessing, the congregation responds with "Amen." In most other communities, the congregation responds by saying "kain yehi ratzon" – "indeed, may this be Your will."

This prayer is also said by the chazzan during the holiday Musaf if no Kohen is in attendance to actually perform the Birkat Kohanim.

Since this prayer is only recited during those prayers which are inherently eligible for Birkat Kohanim, it is not recited during Minchah services, when Birkat Kohanim isn't performed for fear that some of the Kohanim may not be completely sober. On public fast days, when there is no concern of intoxication, this prayer is recited during the Minchah prayer as well.

On the fast of Tisha b'Av, this prayer is not recited by the chazzan during the Shacharit prayer. Blessings must be granted with a joyous heart, which is painfully absent on this morning. During the afternoon Minchah prayer, when the mourning has subsided slightly, the prayer is recited.