Is the Farewell Tawaf obligatory for whoever performed Umrah in Ramadan? And when does the Farewell Tawaf become obligatory?

The majority of scholars hold that the Farewell Circumambulation (Tawaf al-Wada') is recommended for the performer of 'Umrah, not obligatory. Therefore, there is no sin upon one who does not perform the farewell circumambulation while performing 'Umrah. As for the pilgrim performing Hajj, it is obligatory according to the majority, based on the Prophet's (peace be upon him) saying: "Let no one of you depart until his last act is circumambulating the House." The Farewell Circumambulation is prescribed upon leaving Makkah because it is the last act performed by the pilgrim.