GST Verification
API

A practical guide to the GST verification API

The GST verification API confirms that a GSTIN is real, active and registered to the business you think it is. Because almost every business that trades at scale in India is GST-registered, the GST verification API is often the first check in business onboarding, vendor onboarding and merchant underwriting.

Understanding the GSTIN

A GSTIN is a 15-character number. The first two digits are the state code, the next ten characters are the business's PAN, the thirteenth character identifies the registration number for that PAN within the state, the fourteenth is usually the letter Z, and the last character is a check digit. That structure is useful: the PAN embedded in a GSTIN can be cross-checked against the PAN the business gave you, and the state code should match where the business says it operates.

What to check in the response

• Registration status. Treat cancelled and suspended registrations as a stop, not a warning.
• Legal name and trade name. Compare both with what the applicant entered; the trade name is often the brand customers know.
• Taxpayer type. A composition taxpayer and a regular taxpayer are different kinds of business, which matters for some underwriting rules.
• Principal place of business. Compare it with addresses on other documents.

Designing the flow around the GST verification API

Ask for the GSTIN early, validate its format as the user types, and call the GST verification API when the form is submitted. If the business has several GSTINs, one per state, decide whether you need all of them or only the one for the state you will deal with. Store the response with the date of the check, because registration status can change; for long relationships, re-run the GST verification API periodically rather than relying on the result from onboarding day.

Combining checks

The GST verification API works best alongside a PAN check and, for companies, a CIN lookup. Each confirms something different: GST shows tax registration and activity, PAN confirms the underlying entity, and the CIN shows corporate registration. Used together, they give a reliable view of a counterparty before money or goods move. You can read the official GST registration rules on the GST portal, which is the system the GST verification API ultimately reflects.

Common mistakes with the GST verification API

The most common mistake is checking only that a GSTIN exists. A valid GSTIN belonging to a different business proves nothing about the applicant, so always compare names. The second is treating the GST verification API as a one-time check; a business that was active at onboarding can later be cancelled, which is why periodic re-checks matter for vendors and merchants you keep paying.