The Official Website of Grand Ayatollah Makarem Shirazi

If a man intends to marry a woman who is known to be a Muslim and thus knowing the Islamic laws of marriage he does not need to ask her whether she has completed her term of Iddah However, if she does not know the relevant Islamic laws he needs to ascertain that she has completed her Iddah It also should be kept in mind that whenever the ruling of Iddah is applicable it includes even the women of the ahl al-kitāb A question What is the ruling for marrying a woman during her term of Iddah? This might occur in different ways 1. If either the man or the woman knows that the woman is still in her Iddah and that marrying a woman during her Iddah is forbidden then it will be permanently prohibited for that man to marry that woman 2. If none of them knew that the woman had not completed the Iddah Term or that getting married during the term of Iddah is prohibited their marriage will not be prohibited if they have not yet had sexual intercourse However, if they have already had sexual intercourse it will be prohibited for them to get married It is noteworthy to mention that if their marriage formula has been recited by their representative their marriage will not become permanently prohibited under either of the above mentioned cases They only need to wait until the woman's Iddah is completed and then they can get married