There is an agreement among Muslim scholars that if the pilgrim has not passed the miqat, which is the particular place from which one enters the state of ihram, he or she may change the intention of ihram. However, if the pilgrim has passed the miqat, some Muslim scholars state that changing the intention in this case is not valid while others state that it is still valid.
Sheikh `Atiyyah Saqr, former head of Al-Azhar Fatwa Committee, states the following: Muslim scholars are unanimous that if the pilgrim has not passed the miqat, he or she may change the intention of ihram, for the pilgrim then has not yet undertaken any of the duties of Hajj or `Umrah.
Hoewver, If the pilgrim has passed the miqat, the scholars differ as to whether changing the intention in this case is valid or not. Some scholars are of the opinion that it is not permissible for the pilgrim in this case to change his or her intention, while some others see that he or she may do so. The latter give as evidence for their view the hadith reported by Muslim on the authority of Jabir ibn `Abdullah to the effect that they went with the Prophet (peace and blessings be upon him) during the Year of Farewell Pilgrimage to Makkah intending Hajj, but after circumambulating the Ka`bah and going between the Safa and Marwa, the Prophet (peace and blessings be upon him) said, “Had I not brought the sacrificial animal along with me, I would have put on ihram for `Umrah. So, who among you has not brought the sacrificial animal with him, he should put on ihram for `Umrah.” Upon that Suraqah ibn Malik ibn Ja`sham said, “Messenger of Allah, will we do this for this year or for years to come?” The Prophet (peace and blessings be upon him) answered, “For years to come.”
Based upon this hadith, the latter view seems to be preponderant over the former. Hence, it is permissible for the pilgrim to change the intention of ihram even after passing the miqat, and consequently there is no expiation required from him or her.
Allah Almighty knows best.