PAN-Linked GSTIN Discovery and Verification for Merchant Onboarding
A digital GST verification layer built into a Flutter merchant app and a Spring Boot microservices backend, discovering every GSTIN linked to a merchant's verified PAN in one step, validating manual entries in real time, and feeding verified GST status straight into KYC routing, onboarding and tax-accurate commission invoicing.
1-tap
GSTIN discovery from the merchant's verified PAN
2
Verification providers covering onboarding and profile updates
0
Manual GST tax calculations on commission invoices
WhatsApp messaging gets complicated at scale.
Many merchants on the platform are GST-registered, and some hold more than one GSTIN across states or business lines. GST data mattered in three places: it determined which business proof documents a merchant had to upload, it was part of the KYC package sent to the payment partner for QR onboarding, and it decided whether GST had to be added to the commissions paid out to the merchant. Yet GSTINs were collected as free text. Merchants mistyped them, picked the wrong one, or did not know their GSTIN at all, and there was no check that the GSTIN actually belonged to the PAN on record. Finance teams then had to work out tax treatment by hand for every payout.
Challenge 1
GSTINs were typed in manually, leading to format errors and numbers that did not exist on the GST portal
Challenge 2
Merchants with multiple registrations often did not know which GSTIN to provide
Challenge 3
Nothing confirmed that a GSTIN was actually linked to the merchant's verified PAN
Challenge 4
GST-registered and non-registered merchants were asked for the same documents, adding friction for both
Challenge 5
Commission invoices needed the correct CGST, SGST or IGST split, and this depended on the state code inside the GSTIN
Challenge 6
Merchants who registered for GST after onboarding had no self-serve way to add a verified GSTIN
Reusing a verified PAN to discover GSTINs is faster for merchants and more trustworthy than free-text entry
Empty results need a designed path: "no GSTIN found" should lead to a manual option, not a dead end
Storing the full verified payload with timestamps makes GST data auditable long after onboarding
Deriving tax treatment from the verified GSTIN keeps commission invoices accurate without manual review
Built with technologies we trust.
Project Goals
The Outcome
We built a digital GST verification capability for a merchant and lending connector platform, where small businesses onboard to accept UPI QR payments and refer customers for loan products. GST verification sits inside the Business Proof step of merchant onboarding. Instead of asking a merchant to type a 15-character GSTIN, the app asks one question, "Are you a GST holder?", and with the merchant's consent the backend searches the Authify eKYC service for every GSTIN registered against the PAN that was already verified earlier in the journey. The merchant simply picks the right GSTIN from a list. Verified GST status then decides which KYC documents are requested, is reported to the payment partner as a straight-through-processing flag during onboarding, and drives CGST, SGST or IGST on every monthly commission invoice.
Conclusion & Impact
"This project showed that GST verification works best when it builds on identity data the platform already trusts. By discovering GSTINs from a verified PAN instead of asking merchants to type them, we removed the most error-prone step in business proof collection and guaranteed that every discovered GSTIN belongs to the right business. Wiring that verified status into document routing, partner onboarding and automated invoicing turned GST from a form field into a reliable input for compliance and payouts."
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