Halakhah к Негаим 4:13

From its laws is, for example, that which they, may their memory be blessed, said that a woman that has given birth does not bring her sacrifice on the fortieth day for a male and on the eightieth day for a female, but rather on the morrow, which is the forty-first day, and likewise the eighty-first day, as it is stated, "On the completion of the days of purification" - meaning to say that they are totally completed. And if she brought it during the days of completion, she has not fulfilled her obligation (Zevachim 112b). If the time has passed and she did not bring her atonement, she brings it after the time. And the whole time that she has not brought it, she is forbidden to eat consecrated foods - and as they, may their memory be blessed, said (Mishnah Negaim 4:3), "[When] she brought her atonement, she eats from consecrated foods." And all those lacking atonement have the same status in this regard. And [regarding] all those that are obligated to bring a sacrifice, we may not bring their sacrifice without their consent; except for [the sacrifice of] those lacking atonement, which does not require consent of the owners (Nedarim 35b). And the rest of its details are in Tractate Niddah (see Mishneh Torah, Laws of Offerings for Those with Incomplete Atonement 1).