You should have appeared for the Class XII (or equivalent) exam for the first time in all the subjects in either 2015 or 2016. But, if your Class XII (or equivalent) examination Board results for the academic year 2013-14 were declared after June 2014, then you are eligible to appear in JEE (Advanced) 2016.
Performance in Class XII
You should be within the category-wise top 20 percentile of successful candidates in your respective Class XII (or equivalent) board examination. OR you should secured 75% (for GEN or OBC-NCL) or 70% (SC, ST or PwD) of aggregate marks in the Class XII (or equivalent) Board examination.
You should have been born on or after October 1, 1991 if belonging to the GEN or OBC-NCL category and on or after October 1, 1986 if belonging to the SC, ST or PwD category.
Number of Attempts
You can attempt JEE (Advanced) two times and that too in consecutive years. It should be your either first attempt or second consecutive attempt.
Previous Admission in IITs or ISM
You should not have been admitted or even accepted the seat by paying seat acceptance fee at any of the IITs or ISM in the past.