GSTIN stands for Goods and Services Tax Identification Number. It is the 15-character identifier that the GST system issues to a person or business once their GST registration is approved. Every tax invoice raised under GST, every GST return filed and every input tax credit claim is tied back to a GSTIN.
If you have ever looked at a bill from a shop, a hotel or an online marketplace and seen a long alphanumeric code printed near the seller name, that code is almost certainly a GSTIN.
Why GSTIN exists
Before GST, an Indian business could hold several separate tax identities at once: a VAT/TIN number from its state, a service tax registration, an excise registration and so on. GST replaced most of those with a single registration per state, and GSTIN is the number attached to that registration.
That gives GSTIN two useful properties:
- It is unique. No two registrations share a GSTIN.
- It is meaningful. Unlike a random account number, parts of a GSTIN describe the registration it belongs to.
The 15 characters, one by one
A GSTIN always has exactly 15 characters. Using a generic placeholder such as 22AAAAA0000A1Z5, the parts break down like this:
- Characters 1-2 — state code. A two-digit number for the state or union territory that issued the registration. 27 is Maharashtra, 29 is Karnataka, 33 is Tamil Nadu, and so on.
- Characters 3-12 — PAN. The ten-character Permanent Account Number of the registered person. This is why a company and its GSTIN are always linked to the same PAN.
- Character 13 — entity number. Which registration this is for that PAN inside that state. The first is normally 1; further registrations run 2, 3 and onwards, then into letters.
- Character 14 — Z. A fixed placeholder character in the standard format.
- Character 15 — check digit. A character calculated from the other fourteen. It lets software detect most typing mistakes before a lookup is ever attempted.
Because the PAN sits inside the GSTIN, one PAN can have several GSTINs — one for each state where the business is registered. A company operating in four states will hold four GSTINs that differ only in the state code and the entity number.
What a GSTIN does not tell you
A GSTIN encodes identity, not behaviour. On its own it does not say whether the registration is currently active, whether returns have been filed, or whether the business is trustworthy. Those are separate questions answered by a lookup, not by reading the number.
The check digit is also only a mathematical test. A string can be perfectly well formed and still never have been issued to anyone. Format validation and verification are two different steps.
Reading a GSTIN in practice
Suppose a supplier gives you a GSTIN beginning with 07. That tells you the registration was issued in Delhi. If the supplier has been describing itself as a Gujarat company, that is not automatically wrong — businesses register wherever they have a place of business — but it is worth a question.
Similarly, if two invoices from what you thought was the same vendor carry GSTINs with the same middle ten characters but different first two, you are dealing with one legal entity billing you from two different states.
Checking a GSTIN
There are two useful checks, in this order:
- Format check. Is it 15 characters, does the state code exist, does the check digit compute? A failure here means the number is wrong as written.
- Lookup. Does a registration actually exist for this number, and what are its current details?
A lookup can return the legal name, trade name, registration status, taxpayer type, constitution of business, registration date, jurisdiction and state. Where a field is not returned, it should be shown as blank rather than guessed.
Where to go next
- Use the GSTIN validator to test whether a number is well formed.
- Use GST number search to run an actual lookup.
- Read the GSTIN format guide for a deeper walk through the 15 characters.
- Read the GST status guide to understand what Active, Cancelled and Suspended mean.
CheckYourGST is an independent service. For anything with legal or financial consequence, confirm the details against the official GST portal.