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The Sages instituted the Musaf prayer to be said on every day in which the Musaf sacrifice was offered in the Temple. Thus, the Musaf prayer on Rosh Chodesh corresponds to the Musaf offering brought in the Beis Hamikdash on Rosh Chodesh.
Are women obligated to Daven Musaf on Rosh Chodesh?
Some Poskim rule that according to those Poskim who obligate a woman to Daven Shacharis and Mincha, she is likewise obligated to Daven Musaf. Other Poskim however rule that women are exempt from Davening the Musaf prayer, even according to the opinion that obligates women to Daven Shacharis and Mincha. Practically, it is customary of many women to Daven Musaf, although those women who do not Daven Musaf certainly have upon whom to rely.
After Shacharis: The time of the Musaf prayer begins immediately after Shacharis. Even if one Davened Shacharis very early in the day, immediately after its time of arrival, nevertheless one may also Daven Musaf at that time. If one transgressed and Davened Musaf before Shacharis he nevertheless fulfills his obligation. [However, initially, one may never Daven Musaf before Shacharis even if this will cause him to miss Davening Musaf with a Minyan, such as he arrived to Shul when the congregation is Davening Musaf. In such a case he is to first Daven Shacharis and then Daven Musaf privately.]
Delaying past 7th hour: One may not delay the Musaf prayer past seven [Zmaniyos] hours into the day, which is one hour after midday. One who delays Musaf past this time is called a Posheia, one who is negligent. Nonetheless, one fulfills his obligation even if he prayed Musaf past this time being that the prayer may be recited throughout the day.
One already Davened Mincha: Even if one already Davened Mincha he may nevertheless still Daven Musaf.
Mincha versus Musaf-Which is one to Daven first: If one delayed Davening Musaf until the time of Mincha arrived, which is from 6.5 hours into the day, and hence now has two prayer obligations in front of him, one of Musaf and one of Mincha, then if it is past the time of Mincha Ketana he is required to first Daven Mincha. Likewise, even prior to Mincha Ketana, if he desires to now eat a meal, whether large or small, then he must precede the prayer of Mincha. If however it is prior to Mincha Ketana and he does not desire to currently eat a meal, then it is disputed as to whether he must precede Mincha or if he may choose to precede Musaf. It is proper to suspect for the stringent opinion and to therefore always be careful to Daven Musaf before the time of Mincha arrives [6.5 hours into the day. Likewise, if this already occurred, one is to precede Mincha to Musaf, as the main opinion follows the stringent opinion.] The entire law above only applies to one who is Davening in private. If however a Minyan is Davening and delayed the prayer of Musaf until 6.5 hours into the day, or even past Mincha Ketana, they are not to precede the prayer of Mincha to Musaf. [The above law applies according to the revealed aspects of Torah. However according to Kabala, one is always to precede the prayer of Musaf to that of Mincha, even if it is past Mincha Ketana. Practically, the widespread custom today is to always precede Musaf to Mincha even if it is past Mincha Ketana and one desires to eat a meal. This certainly applies if one does not desire to Daven Mincha at this time but rather later on. If however one now has a Minyan available for Mincha, then he is to Daven Mincha with the congregation and only afterwards Daven Musaf.]
Mincha versus Musaf-No time to Daven both: If one does not have time to Daven both Musaf and Mincha, such as it is already very close to nighttime, some Poskim rule he is to Daven the Musaf prayer. Other Poskim however question this ruling and argue that one is to Daven the prayer of Mincha. Practically, Admur rules like the latter opinion that one is to Daven Mincha in such a case.
Forgot to Daven Musaf until night-Tashlumin: If one forgot to Daven Musaf throughout the entire day, until nightfall, he cannot make up the prayer with a Tashlumin Shemoneh Esrei as is usually done for other prayers.
If it is already past sunset, but before nightfall, may one still Daven Musaf?
If one Davened an early Maariv, may he still Daven Musaf?
May one Daven the Shacharis Shemoneh Esrei when the congregation is Davening Musaf?
Yes. However this does not consider one to have Davened Shacharis with a Minyan, or even to have Davened Shacharis at a time that the congregation is praying. [It is rather equivalent to Davening in private.] However, some Poskim rule that when Davening Shacharis together with the Musaf Minyan in the same Shul, it is considered as if one is Davening at the same time as the congregation. Other Poskim negate this conclusion.
If one has not yet recited Hallel and the congregation has reached Musaf, what is he to do?
One is to recite Musaf with the congregation and then Daven Hallel afterwards. If however one has not yet Davened Shacharis then he is not to Daven Musaf, as stated above.
If one Davened Mincha prior to Musaf and then Davened Musaf and recalled that he did not say Ya’aleh Veyavo in Mincha, must he repeat the Mincha prayer?
Some Poskim leave this matter in question. [Practically, one is to repeat the prayer as a Nedava.]
What is the law if one intended to Daven Shacharis, and then realized that he accidently Davened Musaf?
Some Poskim rule he has not fulfilled his obligation and is to Daven Shacharis and then repeat Musaf afterwards.
B. Eating before Musaf:
It is permitted to eat after Shacharis, prior to Musaf, all the foods that are permitted to be eaten prior to Mincha once its time has arrived. Thus, one may eat fruits of unlimited quantity, in order to satiate the heart. One may eat up to a Kibeitza [55 grams] of bread, but not more. [Some Poskim rule one may eat even more than a Kibeitza of Mezonos, (however not an amount for which one generally sets a meal on).]
C. Saying a psalm before Musaf:
The Chazan is to recite a Psalm prior to reciting the half Kaddish before Musaf. This Psalm is to be concluded aloud for the congregation to hear. One is to recite at least three verses for this purpose; it is not necessary to recite an entire psalm. At least some of these verses are to be recited aloud.
D. The Nussach:
Keser: The Kedusha of Keser is recited during the Chazan’s repetition of Musaf.
Lechaparas Pesha in leap year: During a leap year, some have the custom to add the words “Lechaparas Pesha” in the middle blessing of Musaf. Practically, the Chabad custom is not to say it even during a leap year.
Vehameracheim: During Modim of Musaf one says “Vehameracheim” with a Vav.
E. The Karbanos in Musaf:
One must mention the sacrifices of the holiday within his Musaf prayer. The custom of Ashkenazi Jewry is to mention the verses of the particular Musaf sacrifice of each holiday on that holiday. Even Sefaradi Jewry is accustomed to mention the particular sacrifices in the Musaf prayer of Rosh Chodesh.
If one omitted the sacrifices: If one did not mention the sacrifices in Musaf, then if he said the words “Naaseh Venakriv Lefanecha Kemo Shekasavta Aleinu Besorasecha” he fulfills his obligation. [If however he did not recite the verses of the sacrifice and also omitted these words then he must repeat the Musaf prayer.]
What is the law if one mentioned the wrong Musaf sacrifice in his prayer?
- Example: What is the law if one Davened the Shabbos Musaf Shemoneh Esrei instead of the Rosh Chodesh Shemoneh Esrei?
If he has not yet concluded the middle blessing, he is to retract and recite the correct blessing and set of verses. If he has already concluded the middle blessing, then if he recited the words “Naaseh Venakriv Lefanecha Kemo Shekasavta Aleinu Besorasecha” some Poskim rule he has fulfilled his obligation and is to continue with his prayer. However other Poskim rule that he does not fulfill his obligation and is to retract to the middle blessing, or to the beginning of Shemoneh Esrei if he already completed his prayer. Practically, we rule like the first opinion and he fulfills his obligation and is to continue with the prayer.
F. What is the law if one began reciting the weekday Shemoneh Esrei instead of Musaf and remembered in the middle?
If in middle of the Musaf prayer one realizes that he is reciting the blessings of the weekday Shemoneh Esrei, he is to immediately stop within the blessing that he is currently holding and continue with the Musaf blessing. However some Poskim argue [and rule that he is to conclude the blessing in which he is currently holding and then continue with the middle blessing of Musaf]. Practically, Safek Brachos Lihakel [and one is hence to follow the first opinion].
What is the law if one Davened the entire weekday Shemoneh Esrei instead of Musaf?
If one accidently Davened the weekday Shemoneh Esrei instead of Musaf, then if he mentioned the Rosh Chodesh Karbanos in any of the blessings of the Shemoneh Esrei, he fulfills his obligation. If he did not mention the Karbanos then he must recite the prayer of Musaf, even if he recited Ya’aleh Veyavo.
In doubt if mentioned the Karbanos: If one accidently Davened the weekday Shemoneh Esrei for Musaf and is in doubt as to whether he mentioned the Karbanos in his Shemoneh Esrei, he is to repeat the Davening.
In doubt if Davened Musaf Shemoneh Esrei or weekday Shemoneh Esrei: If one is in doubt if he Davened the weekday Shemoneh Esrei or Musaf Shemoneh Esrei, it is questionable as to whether he is required to repeat the prayer. [Practically, one is not to repeat the prayer. He is however to have in mind to be Yotzei with the Chazan’s repetition. He is to answer Amen for the Chazan’s blessings, although is not to answer Baruch Hu Uvaruch Shemo. He is to say Kedusha with the congregation, although is not to say the entire Modim [only the first three words].]
What is the law if during Musaf one concluded the middle blessing with the words “Mikadeish Hashabbos”, or “Mikadeish Yisrael Veroshei Chadashim”?
If one mistakenly said “Mikadeish Hashabbos” instead of “Mikadeish Yisrael Veroshei Chadashim” he does not fulfill his obligation and must repeat the blessing. Likewise, if one mistakenly said “Mikadeish Yisrael Vehazmanim” instead of “Mikadeish Yisrael Veroshei Chadashim” he does not fulfill his obligation and must repeat the blessing. If he remembered within Kdei Dibbur then he is to only repeat the last words of “Mikadeish Yisrael Veroshei Chadashim”. If he remembered passed Kdei Dibbur then he is to repeat the concluding blessing. If he remembered after beginning Ritzei, he must return to the beginning of that blessing. If he already concluded Shemoneh Esrei, he must repeat Shemoneh Esrei.
Shabbos Musaf: See Halacha 11A in Q&A!
 Rambam Tefila 1/5
 See M”B 106/4; Kaf Hachaim 286/7
 Magen Giborim, brought in M”B 106/4; See Amudei Or 7; Beis Yitzchak 17; Shoel Umeioshiv 2/52
 Maharam Shick 90; Beshamayim Rosh 89; Tzelach Brachos 26a, brought in glosses of Rebbe Akiva Eiger 106; Teshuvos Rebbe Akiva Eiger 9; brought in M”B 106/4
 The reason: As Musaf is a time dependent prayer. [Tzelach ibid] Alternatively, as women never had a portion in the Musaf sacrifice in the times of the Temple. [Beshamayim Rosh ibid; Maharam Shick ibid] Based on this last reason, women should not be allowed to Daven Musaf, being that it is similar to a Tefilas Nedava which cannot be brought on Shabbos. [Maharam Shick ibid]
 Kaf Hachaim 286/7; Beshamayim Rosh ibid; see also Maharam Shick ibid who although questions this custom writes that that the custom is to Daven Musaf; Tzelach ibid writes they are allowed to Daven
 As in any event many women are accustomed to follow the ruling of the Rambam in 106/1 that they are exempt from even Shacharis and Mincha, and certainly this would apply to Musaf
 Admur 286/1-2
 Admur 286/1; See also 591/13; Michaber 286/1; Tosafus Brachos 26a; Rosh 1; Rambam 3/5
 Admur ibid; Levush 286/1; Tosafus and Rosh ibid
The reason: As the time of the Musaf sacrifice begins immediately after the sacrifice of the Tamid of the morning. [ibid]
 Admur 286/3; Rama 286/1; Rashba Brachos 26; Kaf Hachaim 423/14 in name of Poskim
The reason: Although if the Musaf offering was brought prior to the morning Tamid it is invalid [Zevachim 89a; Menachos 49a] nevertheless, regarding the prayer of Musaf, the Sages were not so stringent to require one to repeat the prayer being that he Davened it at a time that is fit for the offering of the Musaf. [Admur ibid]
 Implication of Admur ibid; M”B 286/5; Kaf Hachaim 286/12
 Maharshag 1/22; Peri Yitzchak 1/1; Ben Porat Yosef 3/3; Igros Moshe 4/68; Minchas Yitzchak 6/36; Shraga Hameir 4/79; Piskeiy Teshuvos 286/4; Likkut Dinei Rosh Chodesh 9 footnote 11
Other opinions: Some Poskim leave in question whether one may Daven Musaf together with the Minyan and then Daven Shacharis afterwards. [Beis Yitzchak 17/2] Other Poskim rule it is better to Daven Musaf with the Minyan and then Daven Shacharis afterwards. [Beir Yitzchak 20, brought in Pischeiy Teshuvah 286; Pischeiy Olam 286/2; Beir Yaakov 286/2]
 Ketzos Hashulchan 78/3
 Admur 286/2; Michaber 286/1; Brachos 28a
 Admur ibid; Michaber ibid; Mishneh Brachos 26a; Megillah 20b
 Admur 286/2 and 286/5
 Admur 286/5; Michaber 286/4; Brachos 28a
 Admur ibid; Rama ibid; Rosh; Rabbeinu Yona
The reason: As Mincha Ketana is the main time of Mincha, and Mincha is a more common prayer than Musaf and therefore has to be preceded under all circumstances, even if one does not plan to eat a meal at this time. This is because any Mitzvah or prayer that is more common receives precedence over a Mitzvah or prayer that is less common. [Admur ibid; Levush 286/4; Zevachim 89a]
 The reason: As in the event that one desires to now eat a meal, he is obligated to now Daven both prayers prior to eating, as it is forbidden to eat a meal before Mincha as ruled in 232/2. Therefore, he is required to precede the Mincha prayer, [due to the rule Tadir as explained above]. [Admur ibid; Michaber ibid]
 Some Poskim rule one may precede Musaf if he chooses. [Stam opinion in Admur; Yeish Omrim in Michaber ibid; Rabbeinu Yonah] Other Poskim however rule that even prior to Mincha Ketana one must precede Mincha in all cases. [2nd opinion in Admur ibid; Stam opinion in Michaber ibid; Tur in name of Tosafus]
 Admur 620/1 writes that “one is Halachicly obligated to Daven Mincha first if he delays Musaf past 6.5 hours.” This implies that Admur rules completely like the stringent opinion here, and even Bedieved one is to suspect for the stringent opinion. This follows the Michaber ibid who wrote the stringent opinion as the Stam opinion. However from the wording of Admur here 286/5 “to suspect and beware” it can be inferred that one is only to initially suspect for their opinion, and not Bedieved. This can be inferred also from the fact that Admur reversed the opinions as they are found in the Michaber, writing the stringent opinion as the Yeish Omrim and the lenient opinion as the Setam. See Kitzur Halachos Umilium p. 83!
 Admur ibid; Michaber ibid; Rambam 3
The reason: In order to prevent the congregation from making this mistake [of preceding Mincha to Musaf] in the future. [Admur ibid]
 Kaf Hachaim 286/36
 Aruch Hashulchan 286/17; Piskeiy Teshuvos 286/10
 See Tur 286; Piskeiy Teshuvos ibid
 Piskeiy Teshuvos ibid
 M”A 286/3; Elya Raba 286/12; Siddur Yaavetz; Machazik Bracha 286/3; Tosefes Shabbos 286/6; Shulchan Atzei Shitim; Shagas Aryeh 19; Chayeh Adam 27/8; Derech Hachaim; Shoel Umeishiv 3 1/161; Machaneh Chaim 1/6; Aruch Hashulchan 286/17; M”B 286/13 in Stam opinion; Kaf Hachaim 286/36; Piskeiy Teshuvos 286/10
 Admur in Kuntres Acharon 286/1 questions the ruling of the M”A 286/3 based on the Yerushalmi Brachos 4/1; So also questions: Tzelach Brachos 26b; Degul Merivava; Beis Meir; Menorah Hatehora 286/3; Nehar Shalom 286/4
 The reason: As Mincha is Tadir and hence differs Musaf even entirely. [Admur ibid]
 Asides for Admur ibid who questions the ruling of the M”A ibid, so rules Admur in Kuntres Acharon 431/1 that “If both Mitzvos are passing, the less common is pushed off”; So also understands Tehila Ledavid 2/18 in Admur ibid; See Likkut Dinei Rosh Chodesh 9 footnote 15
 Admur 286/2 and 108/10; Michaber 108/6 and 286/1; Tosafus Brachos 26a
 The reason: As how can he read the Karbanos in the prayer if the time of the Musaf sacrifice has already passed. The entire reason the Sages instituted to recite the seven blessings of Musaf is only in order to “Neshlama Parim Sefaseinu”, to verbally make up the sacrifice, and thus certainly in this regard if its time has passed its sacrifice is annulled. However by the other prayers, such as Shacharis and Mincha, since they are merely requests of mercy from Hashem, [one can make up the prayer as a Tashlumin] as it is virtuous if one would pray the entire day. [Admur ibid; Tur in name of Tosafus; See M”A 286/3 and Admur in Kuntres Acharon 286/1]
 Admur 286/2 “Until dark/nightfall”; Ketzos Hashulchan 83 footnote 22; Piskeiy Teshuvos 286/3
 The reason: This follows the same law as Mincha, which may be prayed in a time of need until nightfall.
 Ketzos Hashulchan 83 footnote 22
 Piskeiy Teshuvos 286/3
 Admur 90/10; M”A 90/17 [see also M”A 236/3]; Avoda Zara 4b; M”B 90/30
Other opinions: Some Poskim rule that one who Davens Shacharis while the congregation Davens Musaf is considered to be Davening at a time that the congregation is Davening. [Dvar Yehoshua 5/4 in understanding of Tzelach; Teshuvos Vehanhagos 4/31; See P”M 236 M”Z 4]
 M”B ibid in name of Tzelach and Magen Giborim
 M”A 236/3 [There he is discussing one who Davens Mincha in Shul with the congregation who is Davening Maariv]
 Gra”ch Naah in Yagdil Torah 4/1676
 Shaar Hatziyon 422/3
 Shalmei Tzibur p. 229; Kesher Gudal 24/4; Beis Oved 1; Kaf Hachaim 423/14
 Admur 286/4; Michaber 286/3; Brachos 28b
 Admur ibid; Michaber 232/3; M”A 286/17
 M”B 286/8; See Piskeiy Teshuvos 286/8 footnote 60; Regarding similar Halachos we find that one may not eat more than a Kibeitza of Mezonos: See P”M 431 A”A 4 regarding Bedikas Chameitz, recorded also in Mishna Berurah 431/6. Vetzrauch Iyun.
 Piskeiy Teshuvos ibid based on M”B 639/15
 Igros Kodesh 20/283 [printed in Likkutei Sichos 19/485; Shulchan Menachem 2/201; Shaareiy Halacha Uminhag p. 177]; Sefer Hamamarim Likkut 2/316 of Rebbe Rayatz that so was the custom of the Rebbe Rashab; Luach Kolel Chabad; Nimukei Orach Chaim 55; See Admur 54/4; 292/4; See however Darkei Chaim Veshalom 64; M”B 25/59 in name of Elya Raba; Piskeiy Teshuvos 25 footnote 211; In 1988 the Rebbe directed the Chazan to recite a Mizmor prior to Kaddish of Musaf; Rabbi Leibal Groner confirmed with me that this is the practical custom that is followed and that the Rebbe directed to be done, and the Rebbe never retracted from his ruling.
 The reason: According to our custom to wear Rabbeinu Tam Tefillin before Musaf, we make an interval between Uvah Letziyon and the Kaddish said before Musaf. Therefore, a psalm needs to be said aloud before saying the Kaddish of before Musaf as Kaddish may only be recited after a passage of scripture. [ibid; See Admur 54/4; 292/4]
 See Ketzos Hashulchan 16/2 and footnote 6; Ishei Yisrael 15 footnote 100; Custom of Rebbe and Chabad to recite the Mishnayos aloud after Davening; See Hiskashrus 601/19; Siddur Rav Raskin p. 483
Other opinions: Some Poskim rule it is not necessary to recite the Mizmor aloud. [Mateh Efraim 590/38]
 P”M 55 A”A 3 based on Kol Bo 6 and Darkei Moshe 54/1; Alef Hamagen 590/50; M”B 55/3 “A Mizmor or three verses”; Admur 54/4 “One is a to say a few Pesukim”; Admur 292/4 [one verse does not suffice to be an interval between Kaddeishim];
 Admur 54/4 “One is to teach them to say a few Pesukim between the Kaddeishim”
 As stated above from Poskim; Seemingly, one is not required to say all three verses aloud as is seen from the fact that we only conclude the last two verses of Ashrei aloud. However see Ketzos Hashulchan ibid that implies that all three verses are to be said aloud, as one needs a Minyan who learns it.
 See Kaf Hachaim 423/15-17 for different Nusachos of the Musaf prayer
 Michaber 423/3; Admur in Siddur; Custom brought in Admur 25/41; Arizal in Shaar Hakavanos 76; See Kaf Hachaim 423/20-21
Other opinions: The Ashkenazi custom is to recite Nakdishach within the Kedusha of the repetition of Musaf. [M”A 423/4; M”B 423/7; opinion in Admur ibid]
 See Elya Raba 423/6; P”M 423 M”Z 2; M”B 423/6; Ben Ish Chaiy Vayikra 19; Kaf Hachaim 423/18 for the different custom in this matter, and that some say it even not in a leap year.
The reason: As we ask Hashem to forgive us in case we ate Chameitz on Pesach, as perhaps we made a mistake in the leap year calculation. [Taamei Haminhagim Rosh Chodesh]
 Sichos Kodesh 1973 1/329; Likkut Dinei Rosh Chodesh 7/19 and footnote 27; See Toras Menachem 1984 2/1058
 See Shaar Hakolel 10/32; Sefer Haminhagim p. 27
 591/5 and 488/8; Michaber and Rama 591/2
Background of Admur ibid
“One must mention the verses discussing the Musaf sacrifice in every Musaf prayer. This applies to Shabbos, Rosh Chodesh, Yom Tov, Rosh Hashanah and Yom Kippur. The reason for this is because the mentioning of the Karbanos is considered in place of bringing the actual sacrifice. [However one does not need to mention the particular type and number of sacrifices offered on that holiday. Thus] if one mentioned “Naaseh Venakriv Lefanecha Kemo Shekasavta Aleinu Besorasecha” [“the sacrifices that are mentioned in scripture for this holiday”] he fulfills his obligation and is no longer required to mention the particular verses of the sacrifices. For this reason the custom of Sephardic Jewry is specifically not to mention the verses of the Musaf sacrifice [Michaber ibid; Rabbeinu Yerucham] with exception to Shabbos and Rosh Chodesh, in which case people are familiar with verses and will not come to make a mistake. However by the other Holidays [i.e. all Shalosh Regalim, R”H and Yom Kippur-488/8] one does not say the verses of the Musaf sacrifice as they suspect one may come to make a mistake in the prayer and it will confuse him during his prayer. [Tur; Taz 591/1] Nevertheless, in these countries [Ashkenazi Jewry] they do not suspect for this mistake and they are accustomed to mention the particular Musaf sacrifices even on Yom Tov [of Shalosh Regalim, Rosh Hashanah, and Yom Kippur-488/8].” [Admur 591/5 and 488/8; Rama ibid]
Alternative reason behind Sefaradic custom: Alternatively, the reason the custom of Sefarad is to omit the verses by other holidays is because the verses were already read in the Torah as Maftir. However, on Shabbos, the verses of the Musaf sacrifice are not read from the Torah. Likewise, on Rosh Chodesh, although the verses are read, they are read together with other verses and hence did not receive their due honor. [Shulchan Gavoa 488/10; Kaf Hachaim 591/7]
 The reason: The reason for this is because the mentioning of the Karbanos is considered in place of bringing the actual sacrifice. [ibid]
 However from the letter of the law simply mentioning “the sacrifices that are mentioned in scripture for this holiday” suffices, as explained in the background.
 However Sefardic Jewry only mention the particular sacrifices in Musaf of Shabbos and Rosh Chodesh. [see background]
 Admur 591/5; 488/8
Other Opinions: Some Poskim rule that if the particular verses were not recited one does not fulfill his obligation. [Tur in the name of Rabbeinu Tam]
 Implication of Admur ibid
Other opinions: Some Poskim rule that even if he omitted these words he fulfills his obligation, so long as he recited the words “Naaseh Lefanecha Karbnanoseinu” [Ran R”H; Darkei Moshe 423/2; Kaf Hachaim 423/33]
 488/8; See also Admur 100/1
 As ruled in 49/1 [Admur there rules that it is forbidden to recite verses of Torah by heart unless the verses are fluent on the lips of the masses.]
 Chayeh Adam brought in M”B 488/13
 Shoel Umeishiv Mahadurah Daled 2/108; Lehoros Nasan 8/27
 M”B 108/38; 488/13; Sheivet Halevy 4/63; Piskeiy Teshuvos 488/2; See Betzeil Hachochmah 2/68; Teshuvos Vehanhagos 1/388
 Admur 268/3 regarding Musaf of Shabbos, and the same would apply to Musaf of Rosh Chodesh, as explained there
 Stam opinion in Admur 268/3; 2nd opinion Michaber 268/2; Rabbeinu Yona; Semag 19; Rambam 10/7
The reason: As in the Musaf prayer one is not meant at all from the letter of the law to recite all the weekday blessings, but rather only one middle blessing of Musaf alone. [Admur ibid; M”A 268/1] This can be proven from the fact that on Rosh Chodesh and Chol Hamoed, although the Sages troubled one to pray all 18 blessings in the Shacharis, Mincha and Maariv Shemoneh Esrei, nevertheless, in Musaf we only Daven seven blessings. Thus we see that omitting the 18 blessings in Musaf is not due to that the Sages did not desire to trouble us but rather because there is no need for it. [Admur ibid; Taz 268/3]
 2nd opinion in Admur ibid; 1st opinion in Michaber ibid; Rosh 17 in name of Raavad
 Admur ibid; Bach 268/3; Elya Raba 268; M”B 268/5
 Admur 268/7 and 11; 488/8; 591/5; Rama 268/4; Beis Yosef 268; See Kaf Hachaim 268/29; 423/12
 See Admur 268/7 and 11 that one must mention the Karbanos to be Yotzei Musaf, and hence even if he recited Ya’aleh Veyavo he is not Yotzei.
Other opinions: Some Poskim rule that if one recited Ya’aleh Veyavo in the Shemoneh Esrei he is Yotzei Musaf despite the fact that the Karbanos were not mentioned. [See Michaber 268/6 in first opinion and Kaf Hachaim ibid] Based on this, some Poskim rule that he is not to repeat the prayer of Musaf but is rather to listen into the repetition of the Chazan and be Yotzei with him. [Peri Chadash 423; Shalemi Tzibur p. 229; Kesher Gudal 24/5; Beis Oved Hachaim ibid; Kaf Hachaim 423/12]
 Admur 268/9 regarding Shabbos, and the same would apply to Musaf of Rosh Chodesh
Other opinions: Some Poskim rule he is not to repeat the Davening and is rather to be Yotzei with the Chazan’s repetition. [Shalmei Tzibur p. 229; Kesher Gudal 24/6; Beis Oved 3; Kaf Hachaim 423/13]
 The reason: As we assume that he recited the normal dialect of the weekday Shemoneh Esrei which does not include the Karbanos. [Admur ibid]
 Admur 268/9 regarding Shabbos; See M”A 268/5 and 422/4
 Ketzos Hashulchan 78/3 regarding Shabbos, and the same would apply to Musaf
 Ketzos Hashulchan ibid footnote 11; See Admur 124/14
 Ketzos Hashulchan ibid; See Admur 124/2
 Ketzos Hashulchan ibid
 Admur 487/1 regarding Yom Tov; M”A 487/2 and 268/5; Minchas Elazar 3/19 [See Minchas Elazar ibid regarding the contradiction in the M”A in this matter]
The reason: As since one changed from the Nussach of the Sages he therefore does not fulfill the blessing. [Admur ibid]
 Minchas Elazar ibid; So rules regarding Musaf Rosh Hashanah: Machzik Bracha 582/5; Shaareiy Teshuvah 582/6; Shalmei Tzibur p. 308b; Mateh Efraim 582/18; Kaf Hachaim 582/43; Piskeiy Teshuvos 582/11
 Admur 487/1
 Must he repeat from the beginning of the blessing? Some Poskim rule that he is to start from “Baruch…Mikadesh Yisrael..” and is not required to return to the beginning of the blessing. [M”E ibid; Alef Lamateh 582/8; Piskeiy Teshuvos 582/11] However see Admur 487/1 and 3 who rules that once one has delayed past Kdei Dibbur he must return to the beginning of the blessing.
 See Admur 487/1 that one must return to “the beginning of the blessing”