What is a GSTIN and how to read it

A GSTIN (Goods and Services Tax Identification Number) is a 15-character alphanumeric code issued to every business registered under GST in India.

## Structure of a GSTIN

- **Characters 1-2** — the state code. For example, 36 is Telangana, 27 is Maharashtra and 29 is Karnataka. - **Characters 3-12** — the PAN of the registered person or entity. - **Character 13** — the entity number for the same PAN within a state. - **Character 14** — the letter Z by default. - **Character 15** — a checksum character used to validate the number.

## Why the format matters

Because the format is fixed, an invalid GSTIN can often be spotted before any lookup is performed. A valid GSTIN matches the pattern of two digits, five letters, four digits, one letter, one alphanumeric character, the letter Z and a final checksum character.

## Verifying a GSTIN

Format validity only proves the number is well formed. To confirm that a GSTIN is actually registered and active, the number must be checked against an authorised GST data source. Always confirm critical details against official GST sources before relying on them for compliance or invoicing.