Section 83A(4) in The Central Goods and Services Tax Rules, 2017
(4)Registration for the examination and payment of fee. - (i) A person who is required to pass the examination shall register online on a website specified by NACIN.(ii)A person who registers for the examination shall pay examination fee as specified by NACIN, and the amount for the same and the manner of its payment shall be specified by NACIN on the official websites of the Board, NACIN and common portal.