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:
It is not permissible to have anal sex with one’s wife.
Answering your question, the Fatwa Center at Islam Q and A, states:
Islam forbids anal sex, and there is nothing to indicate that it is permissible.
It was narrated from Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace be upon him) said: “The one who has intercourse with his wife in her back passage has disavowed himself of that which was revealed to Muhammad (peace be upon him).” (Abu Dawud)
It was narrated that Ibn `Abbas (may Allah be pleased with him) said: The Messenger of Allah (peace be upon him) said: “Allah will not look at a man who has intercourse with a woman in her back passage.” (At-Tirmidhi)
It was narrated that Khuzaymah ibn Thabit (may Allah be pleased with him) said: The Messenger of Allah (peace be upon him) said: “Allah is not too shy to tell the truth” three times. “Do not have intercourse with women in their back passages.” (Ibn Majah)
Almighty Allah knows best.