In brief: a GSTIN is the 15-character number that identifies a GST-registered business in a particular state. Checking a GSTIN against the GST record confirms the business is registered and active.
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What a GSTIN is
A GSTIN (GST Identification Number) is the 15-character alphanumeric code assigned to every taxpayer registered under India’s Goods and Services Tax regime. The first two characters encode the state code, followed by the taxpayer’s PAN, and the remaining characters are entity- and check-code digits.
Why it’s used in verification
Because the GSTIN embeds the registrant’s PAN, a GST check can confirm both tax registration status and cross-reference it against the underlying PAN in one step — making it one of the fastest, most universal checks for business KYB in India.
Reading and verifying a GSTIN
Each part of a GSTIN carries meaning. The first two digits are the state code. The next ten characters are the business’s PAN. The thirteenth character distinguishes multiple registrations under the same PAN in one state, the fourteenth is usually the letter Z, and the fifteenth is a check digit. A business registered in several states has a different GSTIN in each.
Quick checks before calling an API
- Check the length and character pattern.
- Confirm the embedded PAN matches the PAN the business gave you.
- Confirm the state code matches where the business says it operates.
What the GST record adds
Format checks catch typos, but only the GST record confirms that a GSTIN is registered, active and belongs to the business in front of you. Look at the registration status, legal and trade names, taxpayer type and principal place of business, and compare them with what you have been told.
Keeping GSTIN checks current
Registrations can be cancelled or suspended. For suppliers, sellers and borrowers you deal with over time, re-check the GSTIN periodically rather than relying on the result from onboarding. Official registration information is available on the GST portal.
How to use the number in business checks
When a business gives you its tax registration number, confirm three things before you rely on it: that the number is real, that the registration is active, and that the legal name on record matches the business you are dealing with. The state code at the start and the PAN embedded inside the number also let you cross-check the business’s location and its PAN record.
Run the check at onboarding and again before large payments, because registrations can be cancelled or suspended. Store the result and the date with your vendor or customer record, so you can show which details were confirmed and when.
The same number also appears on invoices, so finance teams can check it each time they add a new supplier. Doing this once at onboarding and again at the first large payment catches most problems, such as a cancelled registration or a number copied from another business, before they turn into rejected tax credits.
Finance teams that build this into their supplier checklist rarely face surprises at return filing time, because every vendor’s registration has already been confirmed.
Store the date of each check alongside the vendor record.
Where a supplier has several registrations in different states, record each one against the right branch or invoice address.
Reviewing these records once a year, and whenever a supplier changes its legal name or address, keeps the vendor master accurate and avoids rejected tax credits later.
Related terms
