GSTIN (GST Identification Number)
A unique 15-digit number assigned to every entity registered under GST, combining the state code, PAN, and a few check digits.
GSTIN is the registration number every GST-registered business is assigned, and it's structured rather than random: the first two digits identify the state, the next ten are the business's PAN, followed by digits identifying the registration number within that state, for businesses registered in multiple states, and check digits. A business with operations in several states will hold a separate GSTIN for each state, all built on the same underlying PAN.
GSTIN has to appear on every tax invoice, GST return, and e-way bill a business generates, and buyers routinely verify it before claiming input tax credit on a purchase, since a supplier's invalid or cancelled GSTIN can block the buyer's own credit claim.
This glossary entry is for general informational purposes only and does not constitute professional tax, legal, or financial advice. Rules and rates change, so consult a qualified Chartered Accountant for advice specific to your situation.