Firstly there is no lower age limit if you want to appear for NATA. Candidates passed/appearing in 10+2 or equivalent exam with a minimum of 50 per cent marks to be eligible for NATA 2017, given that Mathematics is one of the subjects. The candidates passed/appearing 10+3 Diploma with 50% marks (Mathematics as one of the subjects) recognized by any State/Central government. International Baccalaureate Diploma passed/appearing, after 10 years of schooling with 50% aggregate marks (Mathematics as one of the compulsory subject) can also apply.