Q.Why did the introduction of GST require a constitutional amendment, and what role does the GST Council play in the GST framework?

Before GST, the Constitution kept the power to tax goods and the power to tax services largely separate between the Centre and the states, so a shared, simultaneous tax like GST needed a constitutional amendment to make it legally possible, and the GST Council was created to run the resulting shared system. …

Why a constitutional amendment was necessary. Before GST, India's Constitution divided the power to levy indirect taxes fairly strictly between the Union and the states — broadly, the Centre could tax manufacture (excise duty) and services (service tax), while the states could tax the sale of goods (VAT/sales tax), with central sales tax on inter-state sale sitting with the Centre but generally accruing to the state of origin. GST, by design, needed both the Centre and every state to simultaneously levy tax on the very same supply of goods and services (as CGST and SGST together, or as IGST). This kind of concurrent, shared taxing power over the same transaction did not exist under the original constitutional scheme, so a constitutional amendment was required to explicitly create this joint power and to establish the institutional machinery — the GST Council — needed to exercise it in a coordinated way.

The GST Council's composition. The Council is chaired by the Union Finance Minister, with the Union Minister of State for Finance (in charge of Revenue) and the Finance Minister (or another nominated minister) from every state as members. This composition ensures that no single level of government can unilaterally decide GST matters — decisions require the Centre and the states to arrive at recommendations together. …