Work on Rosh Chodesh
The custom is for women not to work on Rosh Chodesh. (Yerushalmi Taanit 1:6, Rashi & Tosafot Megillah 22b, Shulchan Aruch O”C 417:1) The Ramah rules that if the local custom is for women to perform certain types of work and not others, they should follow their local custom. The Ari Hakodesh (Shaar Hakavanot: Rosh Chodesh pg. 76) rules that it is prohibited for women to work on Rosh Chodesh.
This is based on Pirkei D’Rabbi Eliezer, Chapter 45) that describes Aaron’s deliberations when he asked the people to bring gold for the Golden Calf: “If I say bring all your gold and silver, they will bring immediately bring all they have. I will instruct them to bring all the jewelry of their wives, sons and daughters, and it will delay them.” The women refused to hand over their jewelry: “You want to make a Calf that is disgusting to God, something that has no power to save and cannot hear you!” The Holy One, Blessed is He, rewarded them with a higher gift of Rosh Chodesh than the man, a higher holiness that will remind them that they will be completely renewed in the World to Come, just as the moon is renewed and as their bodies renew each month.
The Kabbalists explain that when the women refused to participate in the sin, they repaired some of the damage of the sin of the Tree of Knowledge, and allowed the lower world to regain its ability to influence the Upper Worlds. (Pri Eitz Chaim, Rosh Chodesh, page 106; Mishnat Chasidim, Masechet Rosh Chodesh 4:3)
The Bach rules that a husband may not ask his wife to perform any work on Rosh Chodesh, but the woman may do according to her personal custom.