Dear student,

The refunds for the JoSAA and CSAB rounds related to NIT+ System was initiated from 15th December 2020. You can refer to JoSAA Business rule and CSAB information brochure carefully to assess their eligibility for refunds. The amount will be refunded in the account for which the details had already been provided by the candidates during the registration process.
Usually it takes 3 to 4 days to get a refund or a maximum of 5 days after the initial announcement of the refund.
Also as per my knowledge there is no procedure of refund like form filling, etc. The amount will come back directly into bank account automatically.

Check out the following information brochure of csab 2020 special round for information and the refund fees :-
https://csab.nic.in/WebInfo/File/GetFile?FileId=18&LangId=P