A: Qurbani is compulsory if you have the equivalent of Nisab on any of the three days of Qurbani (i.e. 10th, 11th or 12th of Zul Hijjah). The Nisab amount does need not be in one’s possession for an entire year for Qurbani to be Wajib.
And Allah Ta'ala Knows Best
Shafiq Jakhura (Mufti) and M.D. Mangera (Mufti)
Darul Ihsan Fatwa Dept.