Hello Aspirant,

See it depends upon the year when you have passed your class-12th in regular mode. For taking admission to any of the NITs you have to appear for JEE-Main and should have a good score and along with this you must have your passing certificate which can be maximum of three year earlier not more than this.

It means that if you are going to appear for JEE-Main then your passing certificate of class 12th should be of year 2018 or later.

As per new norms decided by NTA and ministry of education there will be three consecutive years allowed for sitting in JEE-Main after passing out class 12th and theses three year will include the year of passing class-12th.

I hope this information helped you in clearing your doubts.

Good Luck!!