Hi,you can pursue Mtech in CSE after your under graduation in IT by writing computer science as specialization in TANCET exam.You can choose any subject of choice that you want to pursue in your post graduation.Tancet 2021 is expected to be held in May 2021.Kindly refer this link to know about the exam and admission process of Tancet https://engineering.careers360.com/articles/tancet

Best wishes!