The רמ”א (הלכות ראש חודש סימן תכ”ו סעיף ב’) writes that we do not recite קידוש לבנה before Tisha B’Av or before Yom HaKipurim. We do say קידוש לבנה on מוצאי יום הכיפורים when we are in a state of simcha. However on מוצאי תשעה באב or at the end of any other fast day קידוש לבנה is not recited. Also in סימן תקנ”א סעיף ח’ the רמ”א says ונוהגין שלא לקדש הלבנה עד אחר תשעה באב. The ט”ז explains, that the Rema means the day after תשעה באב, like he said in סימן תכ”ו.
The Mishna Berurah explains the reason we don’t say it before תשעה באב, is because we are in a situation of אבילות. We also don’t say it before יום הכיפורים because we are frightened from the דין and are not in a situation of שמחה. After יום הכיפורים when we were זוכה to מחילת עונות we are now בשמחה and recite קידוש לבנה. However in regard to other fast days one must wait until the following evening to recite קידוש לבנה, since he is not yet back to a state of simcha. The דרכי משה also says that in a year when תשעה באב falls on Thursday [like this year] one should wait until מוצאי שבת to recite קידוש לבנה even though it will be ליל י”ב and very close to the end of the זמן. This is the opinion of the Rema.
The גר”א disagrees with the the רמ”א. He holds that קידוש לבנה should be recited right away and one should not wait until after תשעה באב. The reason is because מצוה הבאה לידך אל תחמיצנה – when one has an opportunity to do a mitzvah, it should not be pushed off, rather it should be done right away. This was the מנהג of the חזון איש והסטיפלר והגרש”ז אויערבך זצ”ל. The ערוך השלחן says that the minhag in Lithuania was not to wait until after תשעה באב. It was very cloudy during this time of year, and they were afraid if they waited they may not be able to be מקיים the mitzvah. For those who follow the מנהג הגר”א there is a machlokes if טובים מאורות may be sung after קידוש לבנה. Reb Chaim Kanievsky shlit”a says המנהג להקל, while Reb Shlomo Zalman zt”l holds it is prohibited.
The poskim say that even though מדינא one can say קידוש לבנה by himself, still because of ברב עם הדרת מלך one should wait to recite it with a minyan [according to the חיי אדם three people is also considered ברב עם.] The ביאור הלכה brings from the אשל אברהם that if one knows that he will have a minyan at a later date, then he should wait and not say it by himself. However he should only wait until the tenth of the month.
I am מסופק what the halacha is for someone who is נוהג like the גר”א and recites קידוש לבנה before ,תשעה באב when everyone else in his neighborhood does like the רמ”א and recites it after תשעה באב. Should he recite it by himself because of ,מצוה הבאה לידך אל תחמיצנה or do we say that ברב עם הדרת מלך overrides that, and he should wait until after תשעה באב and say it together with everyone else. [I recently saw quoted from the sefer מנחת שמואל who said in the name of his Rebbi הג”ר חיים וואלאזניר זצ”ל that even those who are נוהג like the גר”א this is only בצינעא and not בפרהסיא. According to this if everyone else is doing like the רמ”א and waiting until after תשעה באב he should do the same.]
There is another area in which the אחרונים disagree with the רמ”א. The רמ”א said that one should not recite קידוש לבנה on מוצאי תשעה באב or מוצאי of the other fasts. All the poskim hold that קידוש לבנה is recited on מוצאי תשעה באב and מוצאי other fasts. The באר היטב (סימן תקנ”א ס”ק כ”ה) brings a reason why we say קידוש לבנה on מוצאי תשעה באב. בן דוד was born on מוצאי תשעה באב and we are sending a message to both the moon and Klal Yisroel that in the future they will be renewed. However one should first eat something before reciting it. This does not apply to Yom HaKipurim since we are בשמחה that we were זוכה בדין. The אליה רבה says that if one will miss saying it with a minyan if he will need to eat something, then he should say it before tasting anything, because ברב עם הדרת מלך.
The minhag is that we recite קידוש לבנה on מוצאי תשעה באב. First everyone goes home to break their fast and then return to shul to say קידוש לבנה together ברב עם. One should change back into his shoes before reciting קידוש לבנה.1
Prepared by R’ Avrohom Yehoshua Ziskind
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1Sources:משנה ברורה,דרשו,פסקי תשובות