GSTIN Format Validator - Verify Any GST Number (2026)

GSTIN (GST Identification Number) is a unique 15-character alphanumeric code assigned to every registered taxpayer under GST. It consists of: State Code (2 digits), PAN (10 characters), Entity Number (1 character), 'Z' (default character), and a Checksum digit. For example, in 27AABCU9603R1ZM, '27' is Hyderabad's state code, 'AABCU9603R' is the PAN, '1' is the entity number, 'Z' is default, and 'M' is the checksum.

To verify a GSTIN, check these components: 1) The first two digits should be a valid state code (01-38), 2) Characters 3-12 should form a valid PAN format (5 letters + 4 numbers + 1 letter), 3) Character 13 should be 1-9 or A-Z representing entity number, 4) Character 14 should always be 'Z', and 5) Character 15 should pass the Luhn mod 36 checksum validation. Our free tool validates all these automatically.

Each part of a GSTIN has specific meaning: Positions 1-2 represent the state code where the taxpayer is registered (e.g., 27 for Hyderabad, 07 for Delhi). Positions 3-12 contain the PAN of the business or individual. Position 13 is the entity number (1-9, then A-Z) for multiple registrations under the same PAN in a state. Position 14 is always 'Z' (reserved for future use). Position 15 is a check digit calculated using the Luhn algorithm.

The GSTIN checksum (15th character) is calculated using the Luhn mod 36 algorithm. Each character is assigned a value (0-9 for digits, 10-35 for A-Z). The algorithm alternates between multiplying values by 1 and 2, sums the digits, and calculates the check character that makes the total divisible by 36. This ensures any single character error or most transposition errors are detected.

Yes, you can verify GSTIN on the official GST portal (gst.gov.in) under 'Search Taxpayer' section. However, our tool provides instant format validation without requiring captcha or internet delays. For automated GSTIN validation during invoice entry, TallyPrime validates vendor GSTINs in real-time. Our Tally customization team can set up advanced validation rules for your business.