-> Deposit the correct GST and apply for refund of wrong GST.
-> No interest to be charged on GST to be paid in such case.
Sec. 77(1) of CGST Act
A registered person who has paid the Central tax and State tax or, as the case may be, the Central tax and the Union territory tax on a transaction considered by him to be an intra-State supply, but which is subsequently held to be an inter-State supply, shall be refunded the amount of taxes so paid in such manner and subject to such conditions as may be prescribed.
Sec. 54(8)(d) of CGST Act
Notwithstanding anything contained in sub-section (5), the refundable amount shall, instead of being credited to the Fund, be paid to the applicant, if such amount is relatable to refund of tax in pursuance of section 77
Sec. 19(2) of IGST Act
A registered person who has paid central tax and State tax or Union territory tax, as the case may be, on a transaction considered by him to be an intra-State supply, but which is subsequently held to be an inter-State supply, shall not be required to pay any interest on the amount of integrated tax payable.