Hello Aspirant,

No there is no any kind of rule for it. So you can go for it if you are eligible. See if you have remaining number of attempts for JEE-Mains then you can surely go for it. But I don't think that there is a need to change from IIT to NIT because IITs are the most prestigious engineering institutions of India until and unless you are having any lower branch in some newer or lower IITs.

However you have to withdraw your admission from the IIT in which you are currently enrolled then only you will be allowed to take admission in NIT and suppose if you do not get any NIT through JEE-Main score in upcoming year then this IIT will work as a back-up option.

For complete details about JEE-Main kindly check out the link given below :-

https://learn.careers360.com/engineering/jee-main/

I hope this information helps you.

Good Luck!!