Tawaf Al-Ifadah is the Tawaf performed by the pilgrim on Dhul-Hijjah 10. The best time to perform Tawaf Al-Ifadah is before noon on the Day of Sacrifice, though there is disagreement among scholars on when the period to perform Tawaf Al-Ifadah ends. It is one the rituals of Hajj and if it is missed, the Hajj is void.
In this regard, the late Sheikh Ibn `Uthaymeen, a prominent Saudi Muslim scholar (may Allah shower mercy on his soul), issued the following fatwa:
Tawaf Al-Ifadah is one of the pillars (essential parts) of Hajj without which Hajj is not complete. If a person does not perform it, then his Hajj is not complete and he has to perform it; so he has to go back—even from his own country—and perform Tawaf Al-Ifadah. In this situation, so long as the pilgrim has not performed Tawaf Al-Ifadah, he or she is not permitted to have sexual intercourse until after Tawaf Al-Ifadah is completed.