Yes, you can give JEE Main after your one year of board exam but it is recommended that you should not waste your year because you can give JEE main 3 times only and if you are appearing in 2018 it means you should pass your 12th class in 2016, 2017 or you will qualified your 12th in 2018. So, if you drop a year you miss one chance.

There are many companies as well who consider your gap. So, don't waste a year atleast you should try for it.

You can check the eligibility critera below for 2018-

-Students who are born on or after October 1, 1993 are eligible to apply for JEE Main 2018.

-Candidates belonging to Scheduled Caste (SC), Scheduled Tribe (ST) and Persons with Disabilities (PwD), must have been born on or after October 1, 1988 to be eligible for JEE Main. Candidates of these categories have been given a relaxation of 5 years.

-Candidates must have passed 12thclass or qualifying exam in 2016 or 2017.

-Candidates who are appearing in class 12thor qualifying exam in 2018 can also apply for JEE Main 2018.

-It is mandatory for candidates to have taken 5 subjects in 12thor qualifying exam

-The 5 subjects for B.Tech/ B.E. are:

1-Language, 2-Physics, 3-Mathematics, 4-Any one of (Chemistry, Biology, Biotechnology, Technical Vocational Subject), 5-Any other subject

-For admissions to NITs/ IIITs/ GFTIs, candidates should have secured at least 75% marks in class 12th exam or be in the top 20 percentile in the class 12th exam conducted by the respective boards.

-For SC/ ST candidates, the eligibility criteria is 65% marks in class 12th.

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A JEE Main candidate can avail 3 attempts for the national level undergraduate engineering entrance exam.

All the Best!!

Candidates can give Jee main thrice and Jee advanced twice consecutively when you are in 12th so if you fulfil this criteria then you are eligible to give the exams. For more information about its eligibility criteria, you can go through the below link-

Jee main eligibility 2018

Hope this helps!!!