Is an 'Umrah, performed at the end of Ramadan and completed after 'Isha, considered to be in Ramadan or in Shawwal, and is Hajj al-Tamattu' obligatory in such a case?

Scholars differ concerning one who performs Umrah before the months of Hajj and completes it within those months, then performs Hajj in the same year: is he considered a mutamatti‘ (one performing tamattu‘ Hajj) or not? The Hanbalis and the more prominent view of the Shafi‘is hold that he is not considered a mutamatti‘ and no sacrificial animal is required of him. The Hanafis and Malikis, however, hold that he is a mutamatti‘ and the sacrificial animal is due from him, with the Hanafis stipulating that most of its rites be performed within the months of Hajj. For the Malikis, performing even part of it within the months of Hajj suffices, even if it is only one circuit of the sa‘y. The Shafi‘is, in their second view, stipulate that all of its rites must be performed within the months of Hajj for tamattu‘ to be achieved. The issue is one of scholarly disagreement, and adopting the second opinion is more preferable and more cautious.