Verify a GST number’s format and checksum, free and instant.
A GSTIN (GST Identification Number) is a 15-character code with a fixed structure: the first 2 characters are a state code, the next 10 are the taxpayer's PAN, the 13th is an entity number (for businesses with multiple registrations on the same PAN in a state), the 14th is always "Z", and the 15th is a checksum character calculated from the preceding 14 using a checksum algorithm called Luhn mod 36.
This tool checks that structure — correct length, correct character pattern, and a checksum that actually matches what the first 14 characters compute to — and looks up which state or union territory the state code belongs to.
This is a structural and checksum check, not proof that a GSTIN is currently active or registered to a real business — a fabricated GSTIN can still pass a checksum check if someone deliberately computes a valid one. For confirmed registration status, legal name, and filing status, use the official GST portal's taxpayer search at gst.gov.in.
No. It confirms the format and checksum are mathematically valid, not that the number is actually registered to a business or currently active. Verify registration status on the official GST portal (gst.gov.in).
It catches typos and transposed characters — most single-character mistakes when copying a GSTIN will produce a checksum mismatch, which is what this tool flags.
The first two digits of every GSTIN are a fixed state code, standardized across India. This tool decodes that portion so you can sanity-check that a customer’s GSTIN matches the state they say they’re registered in.
Those codes are no longer active — 25 (Daman & Diu) and 28 (undivided Andhra Pradesh) were discontinued after later state/UT reorganizations, so a GSTIN starting with either is not currently valid.
Yes — "GST number" is the common everyday term for a GSTIN, and "verification" and "validation" both describe the same structure/checksum check this tool performs.