GSTIN: format, meaning and how to verify it
GSTIN is the 15-character GST identification number given to every registered taxpayer, built from state code, PAN, entity number and a check digit.
Short answer
A GSTIN (Goods and Services Tax Identification Number) is the unique 15-character number allotted to every person registered under GST in India. It is state-specific and PAN-based, so a business registered in three states holds three GSTINs. The GSTIN must be shown on tax invoices and displayed at the place of business.
- Length
- 15 characters
- Basis
- State code plus PAN
- Display
- On invoices and at the place of business
- Verify
- Search taxpayer on the GST portal
How to read a GSTIN
Each character position in a GSTIN has a fixed meaning, which makes it easy to spot obvious errors on an invoice. Take an illustrative GSTIN such as 29ABCDE1234F1Z5, which does not belong to a real business, and read it as follows.
- 29: state code (29 is Karnataka)
- ABCDE1234F: PAN of the business
- 1: entity number for registrations under the same PAN in that state
- Z: default character
- 5: check digit for error detection
When you need a GSTIN
Registration is compulsory once aggregate turnover crosses the threshold, generally ₹40 lakh for suppliers of goods and ₹20 lakh for services, with lower limits in some special category states. Certain persons must register regardless of turnover, including those making inter-state taxable supplies of goods, e-commerce sellers in many cases, and persons liable to pay tax under reverse charge. Registration is applied for in Form GST REG-01 on the GST portal, with Aadhaar authentication or biometric verification.
Why it matters for startups
Customers who are GST-registered need your GSTIN on invoices to claim input tax credit. Before paying a vendor, verify its GSTIN and return-filing status on the GST portal, because credit depends on the supplier's compliance. If you operate in more than one state, you need a separate registration in each state from which you make supplies.
Related services
Sources
Written by the Refogo Editorial Team from the official sources above and checked on 2026-10-31. Laws, rates and due dates change, and authorities often extend deadlines, so confirm your own case with a qualified professional. This is general information, not legal or tax advice. Read our editorial policy or report an error to support@refogo.com.
Common questions
Can one PAN have multiple GSTINs?
Yes. A business gets a separate GSTIN for each state where it is registered, and can hold more than one in a state for separate business verticals.
How do I verify a GSTIN?
Use the Search Taxpayer function on the GST portal to check the name, status and return-filing history.
Is GSTIN the same as GST registration number?
Yes. GSTIN is the registration number issued on approval of the GST registration application.