Place of Supply rules determine whether IGST or CGST/SGST applies, preserving destination taxation and input credit flow. The IGST framework taxes inter State and cross border supplies under the dual GST model to uphold the destination principle and preserve input tax credit integrity. IGST, levied by the Centre, ensures the consuming State receives the SGST component, with rates broadly equal to CGST plus SGST. Correct determination of the place of supply-with distinct rules for goods and services and separate B2B/B2C treatment-is essential to classify supplies as intra State or inter State and to apply appropriate tax heads. Cross utilisation rules allow IGST credit to be used against IGST, CGST, and SGST and vice versa for CGST/SGST toward IGST.