Students are allowed to change their branch at end of 1 year and second year but for that, you need to be wise with your preference order. generally, the student fills BC form in trending order and they fill a lot of choices. At the end of the first year, CSE @ 10, ee/math @9.3-9.5 followed by others, but due to terminations and vacant seats, at the end of the second year, CSE@ 9.5 ee/math @7.5-8. BC is allowed only once. if you get a new branch you have to accept it.
Still scoring a CPI in iitk is a tough job.
one more thing. if you do a BC at end of the second year you'll have to take care of 3-4 department courses of second year. and yeah EE is a real tough branch cAuse of all those guys who just missed cse because of B in a stupid course. Avg CPI of EE is 9+ and avg cpi of IITK is somewhat between 5.5-6.
Plus there if your CPI is less than 6.5, you aren't allowed to hold any post.