Hi,

According to the eligibility criteria for  GAT-B for MSc, you must have completed your graduation i.e 10+2+3 from a recognized university with a minimum of 55% aggregate.

You can refer to this link for complete information regarding GAT-B including important dates, syllabus, eligibility criteria etc: https://university.careers360.com/exams/gat-b

I hope this helped you.