Are women obligated to Daven Musaf on Shabbos, Yom Tov, or Rosh Chodesh?
Some Poskim rule women are obligated to Daven Shemoneh Esrei of Shacharis and Mincha. Other Poskim rule women are not obligated to Daven Shemoneh Esrei of any prayer. Practically, the main ruling follows the latter opinion [and women are obligated to Daven daily Shemoneh Esrei of Shacharis and Mincha]. However, they are exempt from Davening Maariv. The question is now asked as to status of women regarding Musaf, and as to whether they obligated to Daven Musaf just as they are obligated to pray Shemoneh Esrei of Shacharis and Mincha, or are they exempt from Musaf according to all opinions.
B. The law:
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.
It is customary of women to Daven Musaf, although those women who do not Daven Musaf have upon whom to rely.
 See Admur 106:2; Piskeiy Teshuvos 106:1
 2nd opinion in Admur 106:2; M”A 106:2 that so rule majority of Rishonim; Ramban in Hasagos Sefer Hamitzvos 5; Rashi Brachos
 Admur ibid
The reason: Although according to this opinion, Davening Shacharis and Mincha is a time dependent positive Rabbinical command of which women are exempt from fulfilling, as they are exempt from all time dependent positive commands even if Rabbinical, such as Hallel and Kiddush Levana, nevertheless, the Sages obligated them to Daven Shacharis and Mincha being that prayer is a request of mercy. [Admur ibid]
 1st opinion in Admur 106:2 based on Rambam Tefila 1:2 as explained in M”A 106:2; M”B 106:4; See P”M 106 A”A 2
 The reason: This request suffices to fulfill their Biblical obligation being that the Biblical obligation of prayer does not carry any specific dialect or time. Furthermore, it is possible that even the Sages did not obligate them to Daven any further. [Admur ibid; M”A ibid] The explanation is as follows: The Biblical command of prayer is not time dependent and hence applicable to women. However, the Rabbinical aspect of prayer, which is the amount and times is not applicable to women being it is time dependent. [P”M ibid]
 Admur ibid and 101:5; M”A ibid in name of Poskim
 Admur ibid
The reason: As the prayer of Maariv was initially established as a voluntary prayer. Now, although the Jewish people have accepted this prayer upon themselves as an obligation, nevertheless the women have not accepted this prayer upon themselves and majority of them do not Daven Maariv [even] on Motzei Shabbos. [Admur ibid]
 See M”B 106:4; Kaf Hachaim 286:7; Piskeiy Teshuvos 106 footnote 26
 Magen Giborim, brought in M”B 106:4; See Amudei Or 7; Beis Yitzchak 17; Shoel Umeioshiv Tinyana 2:55
 The reason: As just as she is obligated in all the other matters relating to Shabbos, Yom Tov, [and Rosh Chodesh] so too she was made obligated in Musaf. [Shoel Umeioshiv ibid]
 Maharam Shick 90; Beshamayim Rosh 89; Tzelach Brachos 26a, brought in glosses of Rebbe Akiva Eiger 106; Teshuvos Rebbe Akiva Eiger 9; Opinion brought in M”B 106:4
 The reason: As Musaf is a time dependent prayer and, women were only obligated to pray the prayers then incorporate requests from G-d and not prayers of Karbanos. [Tzelach ibid; Maharam Shick 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 the above, women should not be allowed to Daven Musaf on Shabbos and Yom Tov [or even Rosh Chodesh and Chol Hamoed], being that it is similar to a Tefilas Nedava which cannot be brought on Shabbos, especially regarding Musaf [as the Musaf sacrifice can never be brought as a Nedava, and hence even on Rosh Chodesh it cannot be said if exempt]. [Maharam Shick ibid]
 Kaf Hachaim 286:7; Beshamayim Rosh ibid; 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; Or Letziyon 2:7-24; Shevet Halevi 4:12 that they have accepted it upon themselves as an obligation; Yabia Omer 2:6; 9:108-56 that they may choose to Daven Musaf if they want, as it’s a Sfek Sfeika, although writes that it is better for them to hear it from the Chazan
 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