GATE (Graduate aptitude test in engineering)  IIT conduct GATE once in a year in month of  Jan.-Feb. 

Eligibility : for mathematics(MA) - MSc  in mathematics/M.E/M.Tech in related discipline 

AGE : there is no bar on age

scholorship : 25000 for Ph.D

                   12000 for M.tech(computer science,industrial mathematics, information technology)

 gate 2018 official link  : http://gate.iitg.ac.in/