Hello,

There are mainly two ways to join National Investigation Agency, one is through SSC CGL as a sub-inspector, or appear for UPSC exam and secured IPS or IRS Service, and join NIA, in case of no vacancies candidates can join any law enforcement agency, and later on apply for transfer once an official notification is released pertaining to vacancy in NIA, now coming to your question, in order to appear for UPSC or SSC there is no such restrictions of belonging to any specific stream, you need to pass graduation in any field from a recognized university, but there is vast difference between SSC CGL and UPSC, the former is conducted over four stages minus interview, the latter is conducted over three stages of prelims, mains and interview, the written test of SSC CGL in stage 1 and 2 is mostly MCQs based except the descriptive paper whereas in UPSC only prelims is MCQs based, and mains is purely descriptive, and it has an extensive syllabus.