Hello,

If you are from CBSE Boards, you need a minimum aggregate of 75 percentage in your boards. So, if you are having 72 percentage in boards and you wish to take admission in NITs, IITs and IIITs, you need to take improvement examination to be held next year(2020) along with students of Class 12th to get a minimum aggregate of 75 percentage.

I hope it helps. For any further queries, ask me in the comments.