Refund to casual taxable person or non-resident taxable person only after he files all returns :
The amount of advance tax deposited by a casual taxable person or a non-resident taxable person under section 27(2) of CGST Act, shall not be refunded unless such person has, in respect of the entire period for which the certificate of registration granted to him had remained in force, furnished all the returns required under section 39 of CGST Act – section 54(13) of CGST Act.
These are overriding provisions.