India GSTIN validator
How the GSTIN format works
- Format
- 15 chars: state + PAN + entity + Z + checksum
- Example
- 27AAPFU0939F1ZV
Things to watch for
- First 2 digits are the state code
- Chars 3-12 are the holder PAN
^[0-9]{2}[A-Z]{5}[0-9]{4}[A-Z]{1}[1-9A-Z]{1}Z[0-9A-Z]{1}$A GSTIN (Goods and Services Tax Identification Number) is the 15-character identifier every GST-registered business in India is assigned, built from a 2-digit state code, a 10-character PAN, a 1-character entity number, a fixed “Z”, and a checksum character — for example 27AAPFU0939F1ZV. Any business that has registered for GST, whether by turnover threshold or voluntarily, has one, and it appears on every tax invoice and GST return.
The structure is layered on purpose. The first two digits are a state code assigned by the GST Council (27 for Maharashtra, 07 for Delhi, and so on), so you can tell where a business registered at a glance. Characters 3 through 12 are the entity’s own PAN — meaning a GSTIN isn’t an arbitrary number but a wrapper around an identifier the business already held. The 14th character is a fixed “Z” reserved for future use, and the entity-number character before it distinguishes multiple GST registrations a single PAN holder may have within the same state.
How this validator works
This tool checks the full 15-character pattern — state code, embedded PAN shape, entity number, fixed “Z” — and then computes the real Luhn mod-36 checksum GSTIN uses for its final character, entirely client-side. A pass means both the structure and the check character are mathematically valid, not just that the length looks right.
What a pass doesn’t tell you
A checksum pass confirms the GSTIN is correctly formed — it doesn’t confirm the registration is currently active, that returns are up to date, or that the business hasn’t been deregistered since the number was issued. For live registration status, use the GST Portal search, linked below, before treating a GSTIN as proof of an active taxpayer.
Scope: this page and tool cover GSTIN format and checksum validation only — not GST return filing, registration eligibility, or input tax credit rules, none of which a client-side check can tell you.
Content last reviewed 2026-07-07.
GSTIN FAQ
What are the 15 characters of a GSTIN made of?
A 2-digit state code, the registrant's 10-character PAN, a 1-digit entity number (for multiple registrations under one PAN in a state), a fixed 'Z', and a final checksum character — for example 27AAPFU0939F1ZV starts with state code 27 (Maharashtra) and embeds PAN AAPFU0939F.
Does this tool run a real checksum on the GSTIN?
Yes. It computes the Luhn mod-36 check character used to generate the 15th digit of every GSTIN, entirely in your browser, so a pass means the checksum genuinely matches — not just that the number is the right length.
Why does part of my GSTIN look like a PAN?
Because it is one — GSTIN embeds the business's or individual's 10-character PAN directly in characters 3 through 12, which is why a business needs a valid PAN before it can register for GST.