What your GSTIN actually means

A GSTIN is the 15-character identity of a GST-registered business. It is not random; each part means something.

Digit by digit

• 1-2: the state code (for example 27 is Maharashtra, 29 is Karnataka).
• 3-12: the holder's 10-character PAN.
• 13: the entity number for that PAN within the state.
• 14: a default letter (Z).
• 15: a check digit.

The first two digits matter on every invoice, because they decide whether a sale is intra-state (CGST and SGST) or inter-state (IGST).