GSTIN Format Checker

Check whether a GSTIN is structurally valid: 15 characters, state code, embedded PAN, entity code and checksum digit. Format check, not a live lookup.

How it works

A GSTIN is 15 characters: a 2-digit state code, the 10-character PAN of the business, a 1-digit entity code, a fixed "Z", and a checksum. This confirms the structure is right — a useful first check before you put it on an invoice. It does not verify the GSTIN is live and registered; for that, use the GST portal's search.

Frequently asked

What does a GSTIN contain?
A state code (2 digits), the business’s PAN (10 characters), an entity number, a “Z”, and a checksum — 15 characters in total. The PAN is literally embedded in the GSTIN.
Does this check if the GSTIN is real?
No — it checks the format is correct. To confirm a GSTIN is active and belongs to a specific business, search it on the official GST portal.

Retainer validates your client’s GSTIN structure when you add it, and uses the embedded state code to pick CGST/SGST vs IGST for you. Try Retainer free