India, July 31 -- For nearly six years, Unified Payments Interface (UPI) transactions in India have carried a zero-cost promise: no Merchant Discount Rate (MDR), no platform fee, no technology fee.

That promise fuelled UPI's rise from a niche payment rail to a system processing over 2,272 Cr transactions worth Rs.28.92 lakh Cr in June alone - a poster child of India's digital payments landscape.

However, UPI is also increasingly becoming the payments ecosystem's biggest unresolved economic problem.

Recent reports suggest the Centre is weighing a targeted reintroduction of MDR not across the board, but on a narrow slice of high-value transactions by large merchants.

Under the proposal, businesses with an annual turnover of Rs.1 Cr to R...