The UPI Credit Card Integration Stack

NPCI Guidelines and TDR Rules

Under the NPCI guidelines for Credit on UPI, credit cards issued on the RuPay network can be linked directly to UPI applications (such as GPay, PhonePe, and Paytm). However, this introduces standard card network economics onto the zero-MDR UPI rail. Transactions above ₹2,000 are subject to an interchange fee of up to 2.0%, split between issuer, acquirer, and network. To comply with regulatory mandates, developers must enforce the following rules:

• Merchant Categories (MDR Exemption): Small merchants (turnover below ₹20 Lakhs per annum) are exempt from MDR for transactions under ₹2,000. For large merchants, standard interchange applies even for lower tickets.
• Acquirer Routing: Transaction routing must automatically toggle between RuPay Credit (Standard Interchange) and UPI rails based on transaction value and MCC limits.
• Settlement Splitting: The payment gateway API must support passing separate tags for base amount, CGST/SGST on TDR, and final payouts.

MDR/TDR Cost Comparison Table

Startups must budget for interchange fees depending on merchant scale and ticket size. The table below represents the standard transaction fee breakdown:

API Schema and Payload Design

To integrate RuPay on UPI, developers must support the latest NPCI API specification. The payload must explicitly pass the credit payment indicator. Below is a sample payload schema for initiating a merchant payment request through a Decentro or Razorpay gateway integration:

{
  "merchantId": "MERCH_PG_908871",
  "transactionId": "TXN_2026_06_19_001",
  "amount": 2500.00,
  "currency": "INR",
  "paymentChannel": "UPI",
  "upiOptions": {
    "allowCreditCard": true,
    "allowedBinRanges": ["607", "608", "652"],
    "mcc": "5732"
  },
  "callbackUrl": "https://api.yourdomain.in/v1/payments/webhook"
}

Refund Lifecycle and Webhooks

Refunds on credit transactions require reverse-settlement paths. The acquirer must return the interchange fee back to the issuer bank, excluding the GST charges which remain with the government tax pool. Below is the webhook payload sent to the merchant's endpoint once a refund completes successfully:

{
  "eventId": "EVT_RFND_8091817",
  "originalTransactionId": "TXN_2026_06_19_001",
  "refundId": "RFND_2026_06_19_99",
  "refundAmount": 2500.00,
  "status": "SUCCESS",
  "settlement": {
    "reversedTdr": 42.37,
    "gstReversed": 7.63,
    "payoutReversed": 2450.00
  }
}

Best Practices for Acquirer Routing

Startups should implement intelligent gateway routing to minimize transaction costs. If a user selects RuPay Credit on UPI for a transaction below ₹2,000, verify the merchant's MCC. If the merchant belongs to a zero-MDR category, routes should favor direct settlement; otherwise, secondary gateway routes with lower transaction fees should be chosen dynamically. By building direct API integrations with multiple banking partners (like ICICI or Axis Bank), you can bypass standard gateway aggregators and save up to 0.4% in extra platform fees.

Furthermore, reconciliation for RuPay on UPI presents unique challenges due to T+1 settlement cycles and GST invoicing logic. The developer stack must implement automated webhook signature verification to secure payments. Since webhook requests are delivered asynchronously, the payload must be verified using an HMAC-SHA256 signature generated with the client's shared secret. The webhook listener should inspect the X-Razorpay-Signature header (or equivalent gateway header) and match it against the locally calculated hash. This prevents webhook spoofing attacks which could lead to double-spending vulnerabilities or false transaction confirmations.

Additionally, transaction routing algorithms should incorporate dynamic fallback mechanisms. If the primary acquirer bank experiences high API latency or a elevated failure rate (calculated using a sliding window of the last 50 transactions), the router must automatically fail over to a secondary partner bank. This ensures high availability and maintains the overall transaction success rate above 98.5%, which is critical for consumer trust and retention in high-volume merchant settings.