How to Implement GST and Indian Payment Methods in E-Commerce

Map your sales pattern first. Ask whether sales are mostly business-to-consumer or also business-to-business, whether orders are largely intrastate or genuinely interstate, and whether turnover brings the store within scope of e-invoicing.

One published source, ClearTax, says e-invoicing applies to GST-registered businesses whose aggregate annual turnover has crossed ₹5 crore in any year since 2017-18, verified 2026-09-08. That threshold has applied since August 2023. Have your CA confirm the present threshold.

Product mix matters too. Categories can carry different GST rates and HSN codes, so the catalogue and checkout must calculate tax per line item, never as one flat rate across the order. Consider an online furniture store shipping across several states, mixing raw wood pieces and finished upholstered items at different GST rates, so most orders need interstate treatment. With its accountant, the store decides whether turnover already requires e-invoicing or is approaching the threshold, and records that decision before configuring the checkout.

Some points need to be stated plainly. Which GST rate applies to a product, how HSN codes are classified, and whether e-invoicing applies are compliance decisions, not software settings. They belong to the business’s own chartered accountant or registered GST practitioner, and this article only describes what an e-commerce platform typically needs to configure.

The sequence has two steps. First the adviser confirms the applicable rules for the specific business and product range, and only then is the software configured to encode exactly those confirmed rules. Copying tax settings from a generic online guide, without that confirmation, is a common and avoidable source of compliance risk for small online sellers.

After confirmation, the work is mostly mapping. Product tax classes link to the right GST rates and HSN codes, and invoices carry GSTIN, HSN and place-of-supply fields populated correctly. If turnover crosses the confirmed e-invoicing threshold, invoices go through the required e-invoicing process instead of being generated independently by the store.

UPI is close to a baseline expectation for Indian shoppers, alongside cards, netbanking and wallets, all accepted through a licensed payment aggregator rather than integrated one by one. Saved cards rely on tokenisation.

Recurring payments need extra care. One source describes the RBI’s Digital Payments E-mandate Framework, 2026 as requiring additional authentication to register a mandate and for most recurring debits above ₹15,000 per transaction. A higher ₹1,00,000 limit is described as reserved for categories such as insurance premiums and mutual fund payments, not general subscriptions (Reserve Bank of India, Notification, verified 2026-09-08). Check them with your CA and provider.

Refunds must reverse tax too. The customer should receive the accurate net amount including tax, not merely the pre-tax product price, and the credit note should mirror the original invoice. Rounding differences between the displayed order total and the sum of individual tax lines are a common source of mismatches in reconciliation, and they stay invisible unless tested.

Gateway failures need their own tests. The classic case is money deducted from the customer’s account while the order never confirms on the store’s side, which floods support with angry tickets. Also test timeouts and declines.

Tax rates, e-invoicing thresholds and payment-authentication rules can all change from one year to the next, which makes configuration a reviewed item and not a launch task.

Quarterly works for most sellers. Ask the adviser and the payment provider whether anything the store assumes about tax rates, invoice fields, e-invoicing scope or payment authentication has changed since the last review. It prevents a larger scramble later.