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GSTIN Validator
Check a GST number's structure and checksum before you put it on an invoice or claim credit against it.
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Result
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A GSTIN carries its own check digit, so a mistyped number can be caught instantly without going anywhere near the portal.
How the number is built
Fifteen characters: two for the state code, ten for the holder's PAN, one for how many registrations that PAN holds in that state, the letter Z, and a final check character computed from the other fourteen.
What this confirms, and what it does not
A number that passes here is correctly formed and almost certainly transcribed accurately. It does not tell you whether the registration is active, cancelled or suspended, or whose it is. For that, search the number on the GST portal.
Why it matters for input credit
Credit is only available on an invoice from a supplier who is genuinely registered and has filed. Validating the number is the quickest first filter — but the invoice still has to appear in your GSTR-2B before the credit is safe.
Frequently asked questions
What do the 15 characters of a GSTIN mean?
Two digits for the state code, ten characters for the holder's PAN, one digit for how many registrations that PAN holds in that state, the letter Z, and a final check character computed from the preceding fourteen.
Does a valid checksum mean the business is registered?
No. It means the number is correctly formed and almost certainly typed accurately. Whether the registration is active, cancelled or suspended can only be confirmed by searching the number on the GST portal.
Why does my supplier's GSTIN fail the check?
Almost always a transcription error — a zero read as the letter O, or a transposed pair. The check digit is designed to catch exactly this. Ask the supplier for the number from their registration certificate rather than from an invoice header.
Can I claim input credit against an invoice with a wrong GSTIN?
No. Credit requires a valid invoice from a registered supplier, and the invoice has to appear in your GSTR-2B. A wrong number means it will not match, and the credit will be reversed with interest.