There is a woman who is offering expiation for sin by fasting for two consecutive months. She is asking about the days when she cannot fast because of her period. Does she have to make up those days after the two months are over, or what?.


Praise be to Allaah.
 

If a woman has to fast for two consecutive months, and her
period comes, she should stop fasting, then complete her fast, and then make
up the days of her period. This is according to scholarly consensus. 

Ibn Qudaamah (may Allaah
have mercy on him) said: The scholars are unanimously agreed that if a woman
who is fasting two consecutive months gets her period before completing that
fast, she has to make up those days when she becomes pure, because
menstruation is something that cannot be avoided during those two months
unless that fast is delayed until the woman has passed menopause, but there
is a risk that she may not be able to do the fast then.  

From al-Mughni. 8/21 

And Allaah knows best.