The New-moon offering is here also commanded for the first time. The goat as a sin-offering, though mentioned last, would seem in fact to have been offered first (compare the precedents in Exodus 29; Leviticus 5; Leviticus 8; Leviticus 9; Leviticus 14; Leviticus 16). The sin-offering, which Numbers 15:22-26 had been contemplated in cases where a sin had been committed ignorantly without the knowledge of the congregation, was henceforth not to be offered merely at discretion, as circumstances might seem to require, but to be regularly repeated, not less frequently than once a month.
Numbers 28:11-15
11 And in the beginnings of your months ye shall offer a burnt offering unto the LORD; two young bullocks, and one ram, seven lambs of the first year without spot;
12 And three tenth deals of flour for a meat offering, mingled with oil, for one bullock; and two tenth deals of flour for a meat offering, mingled with oil, for one ram;
13 And a several tenth deal of flour mingled with oil for a meat offering unto one lamb; for a burnt offering of a sweet savour, a sacrifice made by fire unto the LORD.
14 And their drink offerings shall be half an hin of wine unto a bullock, and the third part of an hin unto a ram, and a fourth part of an hin unto a lamb: this is the burnt offering of every month throughout the months of the year.
15 And one kid of the goats for a sin offering unto the LORD shall be offered, beside the continual burnt offering, and his drink offering.