Dear student,

You can attempt at JEE Mains three times.Once while appearing for your 12th board or other qualifying exam and two more times after passing 12th or the qualifying exam. But these two attempts need to be in consecutive years right after your class12. so, if you scored the minimum qualifying percentage in class 12 in 2018, and then appeared for jee in 2018 as well as 2019, then you can sit for jee 2019 if you clear cutoff. But if you did not sit for jee in 2018 (that is right after your class 12 exam), then unfortunately you will not be able to sit for jee 2019.

All in aly You will be eligible to give jee if you have given your 12th exam in 2018, then appeared for jee 2018 and then again appeared for jee 2019.