If the Umrah is performed and then the Hajj is postponed to the next year...
If the Umrah is performed and then the Hajj is postponed to the next year, the Tamatu' is invalid. It makes no difference whether the pilgrim remains in Makkah to the following year or goes back to his country for the return journey to Makkah. Similarly, it makes no difference whether he removes the ihram or remains in it to the following year.
As a matter of choice, the ihram for Hajj must be worn in Makkah itself and the best place for it is the Holy Mosque; however, if it is not possible to wear ihram in Makkah, it may be worn wherever possible. The Umrah and Hajj must both be performed by the same person as an agent for one particular person. It is not permissible to engage two agents, for a living or dead person, for Hajj-ut-Tamatu', one to perform the Umrah and the other the Hajj.
Similarly, it is not permissible that one person performs the Umrah on behalf of one person and the Hajj for another. Rule 151: If a pilgrim completes the rituals for Umrat-ut-Tamatu', it is obligatory on him to perform the Hajj. As a matter of precaution, it is not permissible for him to leave Makkah without performing Hajj.
However, if he wishes to do so, even if it is not necessary, and there is no fear of missing the Hajj, and if he is sure he can return to Makkah to wear ihram in time, it is evident that he can depart from Makkah without ihram. And if he is not so sure, it is obligatory on him to wear the ihram for Hajj in Makkah. Only then can he depart and head for Arafat in the same ihram.
It is not permissible for a person who has performed Umrat-ut-Tamatu' to leave Hajj out of choice, even though it is a recommended one. However, if it was not possible to perform Hajj, he should consider it Umrah Mufradah; accordingly, he should perform Tawafun Nisa.
Rule 152: It is permissible for a pilgrim whose obligation is Hajj-ut-Tamatu' to depart from Makkah before the completion of his Umrah; that is, evidently, if he is able to return to Makkah; otherwise, as a matter of precaution, he should not do so. Rule 153: The prohibition against leaving Makkah on completion of Umrah arises if one is to depart from the city for another place. However, the new streets and suburbs, that have sprung around the Holy City, are considered part of it.
Thus, the pilgrim can visit them after completing Umrah, whether or not it was necessary to do so.