Hi Arnab,

The criteria for CSAB special round is the same as JOSAA main rounds. 

There is no relaxation or separate rules for this counseling round. All the rules and eligibility criterion is the same as those of the first main rounds. 

These are the criterion:-

• Students must have a valid JEE Main 2019 rank
• Candidates who participated in JoSAA 2019 but did not get any seat are eligible to apply CSAB 2019
• Candidates who have not participated/registered in JoSAA 2019 are also eligible to apply
• Candidates who have been allotted a seat in JoSAA 2019 but did not report to the college or withdrawn from counseling are eligible to apply in CSAB 2019
• Candidates who have opted for Not to Participate in Special Round after JoSAA are not eligible to participate in CSAB Special Round 2019 

Hope this helps