Hi aspirant,

The eligibilty criteria for jee mains is-Candidates who have passed class 12 or any other equivalent exam in 2018 or 2019 or those who will be appearing in class 12 or any other equivalent examination in 2020 will be eligible to appear in JEE Main 2020. Those who have passed class 12 or equivalent examination in 2017 or before and those who will appear in 2021 or later will not be eligible to appear in JEE Main 2020. Aspirants who have appeared for their class 12 in 2017, failed in 2017 but have appeared again in 2018 and passed are not eligible for JEE Main 2020.. So if you dont give 12 exam this year if you have already applied for same you will be considered as fail so you have only one chance to clear 12 and you can give jee mains in next year not this year. Hope this helps.