Dear Rohit, AIIMS MBBS aspirant must have completed their Class 12 from CBSE/ISC/State Board with Physics, Chemistry, Biology and English as the main subjects. For General and OBC aspirants – 60% aggregate; For SC and ST candidates – 50% aggregate and For PwD candidates - 45% aggregate. It does not talk about a private candidature. So you should be eligible to attempt AIIMS MBBS. I would suggest you to fill in the basic registration. If your basic application is approved, then you can fill in the final registration form. Eitherways for badic registration there is no fee involved.