When Shabbat coincides with Rosh Chodesh, a different haftarah is read: Yeshayahu 66:1-24, and the maftir is BeMidbar 28:9-15. It is distinct from Shabbat Machar Chodesh and Shabbat Mevarkhim, as well as Shabbat ha-Chodesh.
Explorations in Jewish History & Torah Thought