GSTIN
Goods and Services Tax Identification Number
A GSTIN is the 15-character registration number identifying a business in a particular state under GST, built from the state code, the PAN, and an entity and check digit.
The structure is readable, which is useful. The first two characters are the state code, the next ten are the PAN of the business, the thirteenth indicates how many registrations that PAN holds in that state, the fourteenth is fixed as Z, and the fifteenth is a checksum.
Because registration is state-wise, one company operating in four states holds four GSTINs against the same PAN. Movement of its own goods between those states is a supply between distinct persons and is taxable — which surprises businesses that think of it as an internal transfer.
Verifying a customer's GSTIN before the first invoice matters. An invoice raised against a wrong or cancelled GSTIN denies your customer their credit, and you will hear about it.
Key facts
- 15 characters: 2-digit state code + 10-character PAN + entity digit + 'Z' + check digit.
- Registration is state-wise, so multi-state businesses hold several GSTINs on one PAN.
- Registration thresholds are ₹40 lakh for goods and ₹20 lakh for services in most states, lower in special-category states.
- Inter-state supply of goods requires registration regardless of turnover.
- Validity can be checked on the GST portal's search facility.
Who this affects
Every registered business, and anyone invoicing one.
How YarnTally handles it
Customer and supplier records hold GSTIN, and it flows onto invoices and into the GST reconciliation.
See what else it doesReviewed September 2026. This is general information about how these rules work, not tax or legal advice, and thresholds and due dates do change. Check your own position with your chartered accountant before acting on it.