The IGST payment can be done utilizing ITC or by cash. However, the use of ITC for payment of IGST will be done using the following hierarchy,-
First available ITC of IGST shall be used for payment of IGST;
Once ITC of IGST is exhausted, the ITC of CGST shall be used for payment of IGST;
If both ITC of IGST and ITC of CGST are exhausted, then only the dealer would be permitted to use ITC of SGST for payment of IGST.
Remaining IGST liability, if any, shall be discharged using payment in cash. GST System will ensure maintenance of this hierarchy for payment of IGST using the credit.