The marriage contract will be deemed valid and remain intact if the husband becomes Muslim, all the while his wife is from the People of the Book whom he is allowed to marry. The consensus on this ruling is transmitted by Ibn Qudaamah, Ibn al-Qattaan and al-Dameeree.
b. If the wife is not from the People of the Book:
i. If the marriage is not yet consummated: The majority of scholars hold that they must be separated from each other if the husband becomes Muslim and his wife is not from the People of the Book unless she enters Islam. This is the view of the Maliki,  [75] The Maliki Madhab holds the view that if the husband becomes Muslim, a one month or so should be waited before enforcing this separation to give the wife room to enter Islam. If she does not enter Islam within this period, separation is enforced. It is said that the husband must separate himself from her if she refuses to enter Islam after proposing it to her, and regardless of whether this takes place before or after consummating the marriage. Shafi’i, and Hanbali Madhabs. Some scholars reported that it is a matter of consensus among scholars.
ii. If the marriage is already consummated: If the husband becomes Muslim and his non-Muslim wife is not from the People of the Book, and the marriage was consummated, but the wife enters Islam during her divorce waiting period, the marriage contract remains valid. However, if she does not enter Islam during the divorce waiting period, separation will count from the time of her husband’s Islam.  [76] The Hanafi Madhab states that if they live in the Land of Islam (i.e. any country where Islamic law is dominant), Islam should be proposed to the wife. If she refuses to accept Islam, the Muslim Judge shall rule their separation from each other. And  if they live in the Land of War (any land where Islamic law is not dominant and the safety and security granted to Muslims are terminated), they gave a different ruling with more details to it. The Maliki Madhab holds the view that if the husband becomes Muslim, a one month or so should be waited before enforcing this separation to give the wife room to enter Islam. If she does not enter Islam within this period, the Judge shall enforce the separation. It is said that the husband must separate himself from her if she refuses to enter Islam after proposing it to her, and regardless of whether this takes place before or after consummating the marriage  This is the view of the Shafi’i and Hanbali Madhabs, the majority of the people of knowledge and some of the righteous predecessors. It is reported that there is a consensus that the marriage ends if she does not become Muslim before the expiry of the waiting period. [77] This refers to the divorce waiting period.
c. If the husband enters Islam and he has more than four wives:

The scholars are in agreement that it is forbidden for a man who enters Islam while having more than four wives to keep all of them as he can only keep four wives at the same times. The consensus is transmitted by Ibn Qudaamah.
d. If the husband becomes Muslim and is married to a woman whom he is not allowed to marry in Islam:

If a disbelieving man is married to a woman whom he is not allowed to marry in Islam, but then he enters Islam, their marriage contract becomes void and invalid, and they must be separated from each other. This is a matter of agreement among scholars, and the consensus is reported by al-Kasaanee, Ibn al-Qattaan, Ibn al-Qayyim, Ibn al-Humaam, and Ibn ‘Aabdeen.