When is it necessary to repeat the Shemoneh Esrei of Mincha even if Ya’aleh V’yavo was omitted?

On Rosh Chodesh, the passage of Ya’aleh V’yavo is added during each of the tefillos. If it is omitted at Shacharis and Mincha, Shemoneh Esrei must be repeated. At Ma’ariv one is yotzei even if it was omitted, since in earlier times the new moon was never sanctified at night. If a person missed Ma’ariv on Rosh Chodesh and will be davening a make-up tefilla at Shacharis, he should--l’chatchila--include Ya’aleh V’yavo in both tefillos. If, however, he omitted it during the second tefilla, he has still fulfilled his obligation. Since the second tefilla is the make-up for Ma’ariv, the Ya’aleh V’yavo requirement cannot be more stringent than it is for Ma’ariv itself. The make-up tefilla cannot be more stringent than the primary tefilla, either. Therefore, if a person missed Minchah on Rosh Chodesh and davened two tefillos during Ma’ariv, he is still yotzei if he omitted Yaleh V’yavo from the make-up tefilla. Although the second tefilla is a make-up for Mincha, the rules are not stricter than those for the primary tefilla of Ma’ariv.

סי' ק"ח ס"ק כ"ו ביה"ל ד"ה אבל ביאורים ומוספים דרשו 57

How does eating before Havdalah affect Shemoneh Esrei?

On Motzei Shabbos, the passage of Atah Chonantonu is added to Shemoneh Esrei. If it is omitted, Shemoneh Esrei is not repeated unless one subsequently ate before reciting Havdalah. If one missed Mincha on Shabbos, he must daven two weekday tefillos during Ma’ariv. The proper method is to include Atah Chonantonu during the first tefilla and omit it during the second one. This shows that the first tefilla is for the primary obligation and the second one is the make-up. If he omitted it during both tefillos, he is still yotzei both obligations. If, after omitting it during both tefillos, he ate before making Havdalah, it is only necessary to repeat Shemoneh Esrei for the present obligation but not for the tashlumin.

ס"י ס"ק ל"א

Does a Shemoneh Esrei that lacks a critical addition have any validity?

If one mistakenly davened the weekday nusach during one of the tefillos of Shabbos, he is not yotzei and he must repeat Shemoneh Esrei. If one mistakenly recited the weekday text during Mincha and only realized the error after Shabbos was already over, the Rishonim disagree about whether he is obligated in tashlumin during Ma’ariv. The disagreement centers on the following question: When a person omits a timely addition to Shemoneh Esrei (such as the Shabbos nusach) and must repeat it, is the repetition because his Shemoneh Esrei was entirely invalid, or was his tefilla valid but it just required repetition with the proper addition? If it is for the latter reason and his Shemoneh Esrei had a certain level of validity, it would be pointless to repeat it at a time (Motzei Shabbos) when he will not be adding the part that was omitted. Shulchan Aruch rules that in such a case, one should daven tashlumin stipulating that if he is not obligated, his tefilla should be a tefillas nedavah. A similar disagreement and ruling applies if one omitted Ya’aleh V’Yavo during Mincha on Rosh Chodesh and only realized it at night, when it is no longer Rosh Chodesh.

סי"א ס"ק ל"ב-ל"ג ביאורים ומוספים דרשו 65

• There is no tashlumin if one willfully misses davening. If, however, a person was involved in other activities and missed davening--even due to negligence--he is obligated in tashlumin. If one delayed davening due to laziness and not because he was involved in another activity, the poskim disagree about whether he has an obligation of tashlumin.

• If a person was involved in business to prevent a monetary loss and missed davening as a result, he has an obligation of tashlumin.

• If one misses Ma’ariv on Friday night, he should daven two tefillos during Shacharis using the Shabbos morning nusach. If he mistakenly said the Friday night nusach, he is yotzei unless he said the Friday night nusach and followed it up with the morning nusach. (This would show that his first tefilla was the make-up and the second one was the primary.) Others say that he would be yotzei his obligation even in that case. 

• When is Atah Chonantonu said on Sunday morning?

• Is there tashlumin on the night of Shemini Atzeres if one missed Ya’aleh V’yavo during Mincha?

• Is it necessary to repeat the brocha if one began Ya’aleh V’yavo on a typical day?