- Shabbat and Holidays
- Rosh Chodesh
One may work on Rosh Ĥodesh. Ideally, though, one should not do so, as is the law on Ĥol Ha-mo’ed. The rule is that the holier the day, the more it is designated for holy endeavors, and the more one should limit his involvement in work. Thus, all work is forbidden on Shabbat, because it is the holiest of all our special days. Work is also forbidden on Yom Tov (festival), which is a level below Shabbat in sanctity, but one may perform activities that are necessary for food preparation. A level below Yom Tov is Ĥol Ha-mo’ed, when only certain acts are forbidden. Rosh Ĥodesh should rightfully be on par with Ĥol Ha-mo’ed. However, since the twelve tribes of Israel sinned in the episode of the Golden Calf, they correspondingly lost the special quality of the twelve Rashei Ĥodashim of the year. Women, however, did not participate in the sin of the Golden Calf, refusing to give their jewelry in order to help create it. Therefore, God rewarded them in this world and in the World to Come. In this world, God instituted that “they observe Rosh Ĥodesh more than the men do.” God also promised that in the World to Come, they will regain their youthfulness, like the moon that renews itself every month, as it says, “He satisfies you with good things in the prime of life, so that your youth is renewed like the eagle’s” (Tehilim 103:5;Pirkei De-Rabbi Eliezer 45). As a result, women absorb more of the sanctity of Rosh Ĥodesh, and they have thus adopted the custom to refrain from working then. 
In truth, in the time of the Temple, when the Kohanim (priests) brought musaf offerings, some men also would refrain from doing major work on Rosh Ĥodesh. But their practice is no longer binding, because they participated in the sin of the Golden Calf. Women, on the other hand, did not sin, and thus have more of a connection to the sanctity of Rosh Ĥodesh. As a result, their practice remains valid.
Therefore, every woman should refrain from doing certain types of work on Rosh Ĥodesh – knitting, for example – in order to differentiate between Rosh Ĥodesh and ordinary days. It goes without saying that she should not plan to do any big jobs on Rosh Ĥodesh.
Some women go above and beyond and refrain from doing any type of work that is forbidden on Ĥol Ha-mo’ed. This includes sewing, knitting, and fixing things in the house. Cooking, baking, and ironing, however, are permitted, as they are permitted on Ĥol Ha-mo’ed as well. Washing clothing in a washing machine is also permitted, because it entails almost no effort. If the clothes are needed for Rosh Ĥodesh itself, one may wash them even by hand. An employed woman may work on Rosh Ĥodesh, even if she generally follows the practice of those who go above and beyond, because if she misses work regularly on Rosh Ĥodesh, she might lose her job. And even if there is no concern that she will be fired, she may go to work if she needs the money or if her absence will cause her employer to lose money.
 This follows the explanation of Pirkei De-Rabbi Eliezer 45, Tur 417, Perisha 417:1, and Darkhei Moshe 417:1 (quoting Or Zaru’a) explain the issue. R. Ĥayim Vital explains in Sha’ar Ha-kavanot 76b that women correspond to the sefira (kabbalistic “emanation”) of malkhut (kingship) and the moon, both of which renew themselves, while men correspond to tiferet (beauty), which does not renew itself. (Furthermore, malkhut involves a decline, from which it can reach even higher than tiferet. This is alluded to in the verse, “A capable wife is a crown for her husband” [Mishlei 12:4].)
 Tur and Beit Yosef oĥ 417 explain that the main source for this custom is y. Ta’anit 1:6: “Those women who are accustomed not to work on Rosh Ĥodesh – it is a custom.” According to Rabbeinu Yeruĥam, a woman who never followed such a custom need not take it on. However, bhl 417, s.v. “ve-hanashim,” states that according to most Rishonim, all women must keep this custom, but they can fulfill their obligation by refraining from any minimal type of work. If, however, they have a more stringent custom that forbids additional types of work, their custom is binding. Indeed, some act more stringently, and I wrote that this is considered going above and beyond. Eshel Avraham (Buczacz) states that even those who go above and beyond should not treat Rosh Ĥodesh more stringently than they do Ĥol Ha-mo’ed. Therefore, they may wash clothes for the sake of Rosh Ĥodesh, because the reason for the prohibition on Ĥol Ha-mo’ed is only to ensure that people wash their clothes in anticipation of the holiday. Regarding washing machines: Sefer Rosh Ĥodesh 11:7 states that some are stringent, but that R. Shlomo Zalman Auerbach permits it, because it involves no effort.
ahs 417:10 states that a woman may work on Rosh Ĥodesh in order to make a living, and that this is the prevalent custom. Hilkhot Ĥagim 1:5 agrees. This can be derived from a kal va-ĥomer (a fortiori argument): If she is liable to lose her job, or if she needs that day’s wages desperately, she may work even on Ĥol Ha-mo’ed. Thus, it is all the more so on Rosh Ĥodesh, which is a lesser holiday. Some women go above and beyond and forgo working that day if they can do so easily. It seems to me that even women who go above and beyond are lenient when it comes to writing for purposes that are not related to work.
According to Shibolei Ha-leket, when Rosh Ĥodesh is two days long, the custom for women to refrain from working applies only on the second day, the first of the new month. Roke’aĥ maintains that it applies on both days. Mor U-ketzi’a maintains that the custom applies only during the day on Rosh Ĥodesh, not at night. It seems to me that women follow this custom at night as well. See mb 417:4, bhl (end of 417).
bhl 417, s.v. “minhag tov,” states in the name of Baĥ that a husband may not demand that his wife work on Rosh Ĥodesh, but she may work if she desires. As stated above, most poskim agree that a woman should refrain from doing some form of work. Since it is a mitzva for a woman to refrain from working, even though it is not obligatory, it is clear that her husband cannot demand that she work on Rosh Ĥodesh, except for housework, like cooking.
Ĥida (Responsa Yosef Ometz §20) cites Rishonim who maintain that men had a custom as well to refrain from working on Rosh Ĥodesh. He explains that this custom developed because they would bow before God in the Holy Temple. Turei Even (on Tractate Megilla) claims that the custom was based on the musaf sacrifices that were offered in the Temple on Rosh Ĥodesh. Either way, most poskim believe that this custom is not binding (mb 417:2).