Ruling 2531

If a woman whose ʿiddah is three months is divorced at the beginning of the lunar month, she must observe ʿiddah for three complete months. However, if she is divorced in the middle of the month, she must observe ʿiddah for the rest of that month and for the two months after that, and then in the fourth month, she must observe ʿiddah for the number of days that had passed in the first month before she started to observe ʿiddah so that three complete months are observed. For example, if she was divorced at the time of sunset on the twentieth of the month and that month had thirty days, then her ʿiddah would come to an end at sunset on the twentieth of the fourth month. If the first month had twenty-nine days, the obligatory precaution is that she must observe ʿiddah for twenty-one days in the fourth month so that the number of days for which she observed ʿiddah in the first month equals thirty days [with the addition of the days from the fourth month].