Hi,
There are two stages of the counselling in JoSAA 2018 :
1) Withdrawal from counselling : This is the first SIX rounds of the counselling, where you can withdraw from the counselling, and then within two working bank days the amount will be refunded.
2) Non - Withdrawal : In this stage i.e the last two rounds of counselling, you are not allowed to withdraw the allotted seat, but there is no related information regarding the refund. Please keep updated with JoSAA website for further details.