Important , Got a job offer , notice period ?

Im from TCS , I got an offer letter today from citibank for the role of analyst
My question is I'm currently on bench, so if I put my papers tomorrow , will I be asked to serve the 90 days notice period or will I be given an early release , They want me to join in 30 - 45 days . So I'm looking for a early release...who should I mail this about , the HR or The RMG Someone please clarify...