In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
2- Such a person, however, must continue performing the rest of his Hajj rites. He must slaughter a camel and make up for his Hajj the following year.
In his well-known book, Fiqh As-Sunnah, the late Sheikh Sayyed Sabiq states:
Ali, Umar and Abu Hurairah issued a fatwa concerning a man who has sexual intercourse with his wife in the state of ihram, saying: They both must complete their Hajj, but must also make another Hajj the following year and slaughter an animal.
Abu Al-Abbas At-Tabari said: If a muhrim (pilgrim in the state of ihram) has sexual intercourse with his spouse before the first tahallul from ihram, regardless of whether it is before or after Arafah, it will invalidate his Hajj. Such a person, however, must continue performing the rest of his Hajj rites. He must slaughter a camel and make up for his Hajj the following year.
If the wife is in the state of ihram and she accepted what her husband did, she must continue the performance of Hajj, but must also make up for it the following year, and besides, according to the majority of the scholars, must also offer a sacrifice.
According to Ata, some scholars hold that the husband and wife may offer only one sacrifice.
The prominent Muslim scholar, Sheikh Muhammad Iqbal Nadvi, Imam of Calgary Mosque, Alberta, Canada, and Former Professor at King Saud University, Riyad, Saudi Arabia, states:
There are three different situations in this case:
First, if sexual intercourse happens before completing Hajj and after standing on mount Arafah;
Second, if it occurs after completing Hajj and standing on `Arafah, while the person is still in the state of ihram; and
Third, it is during the period in which Hajj is still not over until the end of all Hajj manasik (rituals), while ihram is taken off.
The Shari`ah-based ruling for the first two situations is that there has to be a sacrifice of a whole camel or a whole cow and the person has to repeat Hajj again.
As for the third case, there has to be a sacrifice of goat or lamb, and Hajj is valid and accepted, in sha’ Allah.
Allah Almighty knows best.