is the two rakats after tawaf sunnah or wajib.
is there a difference of opinion between scholars and is a sacrifice neccessary if one does not offer the 2 rakah after tawaf
JAZAKALLAH

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

The jurists differed in opinion about the two Rak’ahs after Tawaaf whether they are a Sunnah or Waajib (i.e. an obligation), so the Hanafi School are of the view that it is an obligation to perform two Rak’ahs after every Tawaaf whether it is an obligatory Tawaaf or an optional Tawaaf. The Maaliki School agreed with the Hanafi School in regard to the Tawaaf that is considered a pillar (when performing the rites of Hajj or `Umrah) or an obligatory Tawaaf according to the most famous of the two opinions in the Maaliki school of jurisprudence. Whereas the Shaafi’i and Hanbali Schools are of the view that the two Rak’ahs after Tawaaf are a Sunnah (recommended). Moreover, the Maaliki School is undecided in regard to the Tawaaf other than the Fardh or Waajib Tawaaf whether the two Rak’ahs are Sunnah or obligatory.

However, the view we adopt here in Islamweb is that they are Sunnah and there is no sacrifice if one does not perform them. Even according to the Hanafi School who are of the view that it is an obligation to perform the two Rak’ahs after Tawaaf, they are of the view that there is no sacrifice if one does not perform them. Moreover, according to the Maaliki School, if one abandons the two Rak’ahs after Fardh or Waajib Tawaaf and returns to his country or goes away from Makkah, he should perform them (wherever he is) and he is obliged to offer a sacrifice which should be done in Makkah.

Allaah Knows best.