The central bank published new guidelines Tuesday capping transaction fees for small merchants using mobile wallet and QR-code payment systems, a move officials said would encourage wider adoption outside major cities.

Under the framework, payment providers must settle merchant transactions within 24 hours and publish fee schedules publicly, a requirement several fintech firms said they already meet. The cap applies to transactions under a set threshold, targeting small shopkeepers who currently pay some of the highest relative fees in the payments ecosystem.

“A lot of small vendors have been reluctant to accept digital payments because the fees eat into thin margins,” said a payments-sector consultant. “Capping fees at the low end is a direct way to change that calculation.”

The guidelines also require providers to offer a grievance-redress mechanism for disputed transactions, addressing a common complaint from merchants about delayed refunds.

The rules take effect in 90 days. Industry groups have broadly welcomed the move, though some have asked the central bank to clarify how the rules will apply to cross-border payment apps operating in the market.