Dear candidate,

To secure a seat in IIT Madras you must fulfill at least one of the following criteria:

• Besides JEE advanced or mains, if you fall under the top 20 % of the candidates who successfully cleared their respective 10+2 board examinations then you can easily get in. (min of 75% is a necessity overall)
• or have achieved the minimum cut off marks in your respective categories in JEE advanced, thus you should clear JEE advanced and must have a decent rank.
  (The admission depends upon the seats remaining after each counselling.)

The cut off percentile are provided in the link below: https://engineering.careers360.com/articles/jee-advanced-cutoff-for-iit-madras