Dear Shri Varaprasad Garu,
It is Banks board fix the additional interest rate at 0.50%(or more) for senior citizens and not by GOI or RBI/IBA .
While RBI sets the Repo rate banks have freedom to set their own differential deposit interest rates to attract senior citizens.
As per Master Circular of RBI on the subject :
2.01."Banks have been permitted to formulate, with the approval of their
Boards of Directors, fixed deposit schemes specifically for resident Indian
senior citizens offering higher and fixed rates of interest as compared to
normal deposits of any size. "
Regards
Mohan.P