For board toppers, direct admissions are there but required fees will be there.

Officially, below details are declared -

"In the past, admission process of the Institute always ensured guaranteed admission to all the students who obtained first ranks in their respective board examinations. This has given a very vital input of highly meritorious students from all over India. First rank students of all the central and state boards in India for the year 2018 will be given direct admission to the program of their choice, irrespective of their BITSAT-2018 score as per the eligibility criteria mentioned in their brochure. Further details about this scheme will be available at BITS admission website by 1 st of May 2018". 

Good Luck!!!