GST input tax credit use

Summary: You must prioritize exhausting your IGST credit balance against your IGST output liability first; any remaining IGST credit can then be applied to CGST or SGST liabilities in any order. Only after IGST credit is fully depleted can you use CGST credit for CGST (then IGST) or SGST/UTGST credit for SGST/UTGST (then IGST). Direct cross-utilization between CGST and SGST remains prohibited.