Ata narrates from Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) that if a husband and wife have intercourse while both are in the state of ihram, they shall both complete their Hajj, but they must perform Hajj again the following year from where they had entered ihram, and they shall remain apart until they have completed their Hajj.
Ata said: Whether the woman complied or was forced, one sacrifice is due from the husband and wife together.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9780