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A payment either works or it does not. That is the entire experience from the outside. What the invoice shows you is a single number, and what the customer sees is a confirmation screen. Neither reveals the four or five separate parties that took a cut on the way through.
Every card transaction passes through five distinct fee layers. The pricing model your provider uses does not change which layers exist. It only changes which of them you see itemized [1].
The layers at the top of that table are set by the card networks and move for nobody. The layer at the bottom is the one that determines whether a cross-border transaction costs roughly what a domestic one does, or several times more.
Interchange is the fee the acquiring bank pays to the cardholder's issuing bank on every card transaction. It is set by Visa and Mastercard through published rate tables, and no party in the payment chain can alter it [2]. It is typically the largest single component of a domestic transaction.
The rate varies by card type, transaction method, and geography. In the EU, consumer card interchange is capped at 0.2% for debit and 0.3% for credit under the Interchange Fee Regulation [3]. In the US, interchange is uncapped and typically runs from 1.0-2.5% depending on the card product. A UK consumer debit card carries roughly 0.2%. A US business rewards card can carry 2.5% [4].
This matters for a reason that has nothing to do with pricing conversations. Interchange is why the same product, sold at the same price, costs a merchant a different amount depending on which card the customer happened to reach for. It is the clearest demonstration that payment cost is a property of the transaction, not of the provider.
What does move interchange is the data attached to the transaction. Sending Level 2 and Level 3 data on B2B payments can qualify a transaction for a lower interchange category. 3D Secure authentication qualifies transactions as lower risk. Prompt settlement avoids downgrade surcharges [2]. These are transaction-level engineering decisions rather than commercial ones, and they are available to any merchant regardless of who processes their payments.
On domestic transactions, this layer does not exist at all. On cross-border transactions it is frequently the largest one, and it is the only layer that never appears as a line item.
When a customer pays in one currency and the merchant settles in another, a conversion happens somewhere in the chain. The difference between the mid-market reference rate and the rate applied at conversion is the FX spread. It is embedded in the exchange rate rather than charged as a fee, which is why it stays invisible on an invoice even when it is the largest cost in the transaction [4].
The size of that spread is a function of the corridor, not of anyone's generosity. Major pairs like USD/EUR and USD/GBP are deep, heavily traded, and tightly priced. Emerging market pairs are thinner, involve fewer counterparties willing to hold the currency, and price accordingly. Converting into a freely floating, deeply traded currency and converting into a managed, thinly traded one are not the same operation and do not cost the same.
The number of parties touching the money matters as much as the currency pair. A payment that crosses three correspondent banks is priced more than once on the way through. The stablecoin sandwich settlement model exists largely because collapsing that chain removes the intermediate steps that each carry a spread.
Every layer in the stack gets more expensive when the transaction crosses a border, and the layers compound.
When the customer's issuing bank sits in a different country from the acquiring bank, the card networks apply higher interchange rates and add cross-border scheme fees. The acquirer carries additional cost for the same transaction. And the FX spread, which was zero domestically, now applies [2].
A transaction that costs roughly 2% domestically can cost several times that cross-border once every layer is accounted for [4]. This is not a pricing failure or a provider being opportunistic. It is what the transaction actually costs to move through the infrastructure it has been routed through.
Which points at where the real lever sits.
The most consequential variable in cross-border payment cost is not what any individual layer is priced at. It is whether the transaction is processed as a domestic transaction or a foreign one in the first place.
Local acquiring means processing through an acquiring entity in the customer's own country. The issuing bank then sees a domestic transaction rather than a foreign one. The cross-border interchange premium does not apply, because it is no longer a cross-border transaction. The cross-border scheme fees do not apply. And because settlement happens in local currency, FX conversion moves from the transaction layer to the settlement layer, where it can be handled once in aggregate rather than repeatedly on every individual payment.
The revenue effect is larger than the cost effect, and it is the part most businesses miss. Issuing banks apply stricter fraud scoring to foreign transactions, so cross-border authorization rates run materially below domestic ones. Data across providers shows local acquiring improving cross-border approval rates by 16-20% [6]. On meaningful volume, transactions that were previously being declined and are now approved outweigh any individual fee line by a wide margin.
This is why the cost conversation and the conversion conversation are the same conversation, and why treating payment cost purely as a procurement exercise misses where most of the money actually is.
Both pricing models contain all five layers. The difference is visibility, not total.
Flat-rate pricing bundles everything into a single percentage plus a fixed per-transaction fee. It is predictable and simple to forecast, which for many businesses is worth more than granularity. The trade-off is that a low-interchange EU debit card and a high-interchange US rewards card are billed identically, so the blended rate is doing the work of smoothing the difference.
Interchange-plus pricing separates pass-through interchange from the provider's margin. Each transaction is billed at its actual interchange plus a defined margin. It is less predictable month to month, because the card mix moves, but it makes the underlying structure visible [5].
Neither model is universally better. Flat-rate suits businesses that value forecastability and have a stable card mix. Interchange-plus suits businesses whose card mix skews toward lower-interchange products, where a blended rate would be working against them. The right answer depends on the shape of the transaction base, not on which model is cheaper in the abstract.
For businesses thinking about how a gateway fits a cross-border operation more broadly, including acceptance breadth, authorization performance, and payout capability, our international payment gateway guide covers the wider evaluation.
Thailand's shift to digital payments is the most complete in Southeast Asia. Account-to-account (A2A) payments captured 44% of e-commerce transaction value and 43% of point-of-sale value in 2025, the highest A2A share of any market in the region [1]. Cards remain relevant for higher-value purchases and international transactions, but PromptPay has become the default payment method for the majority of Thai consumers.
Thailand's mobile payments market is estimated at $34.08 billion in 2026, growing from $29.73 billion in 2025 at a CAGR of 14.62% through 2031 [2]. Three digital bank licenses were granted in April 2025 (Krungthai-AIS-Gulf-OR, SCBX-KakaoBank-WeBank, and Ascend Money-Ant International), adding competitive pressure that will deepen wallet adoption further [2].
PromptPay is Thailand's national QR-based payment system, overseen by the Bank of Thailand and operated through National ITMX. It allows users to send money instantly using mobile numbers, national ID numbers, or merchant QR codes.
The numbers define its dominance: 74 million registered users and over 74 million transactions processed daily [1]. Person-to-person transfers are free, a deliberate policy by the Bank of Thailand to drive financial inclusion. Merchant acceptance is embedded into every domestic bank app, making PromptPay as ubiquitous as cash was a decade ago.
PromptPay transfers captured 41.10% of Thailand's mobile payments market share in 2025 [2]. The system's strength comes from its status as public infrastructure rather than a commercial product. Unlike private wallets that compete for users, PromptPay sits beneath every bank and wallet, creating a universal acceptance layer.
For international businesses, the practical consequence is that a checkout without PromptPay loses access to 44% of Thai e-commerce spending. Integrating PromptPay through a payment gateway with Thai coverage is the single highest-impact action for conversion in this market.
TrueMoney holds approximately 16.8% of Thailand's wallet market share and serves a fundamentally different population segment than PromptPay. With 39,000 agent outlets across Thailand, TrueMoney functions as a cash-in network that converts physical cash into digital payments for consumers who do not have bank accounts or prefer not to use online banking [2].
TrueMoney's mobile wallet CAGR is 16.2%, and it could expand the Thai mobile payments market by $13.4 billion between 2026 and 2031 as it penetrates cash-heavy provinces outside Bangkok [2]. For international businesses targeting the Thai mass market beyond urban Bangkok, TrueMoney adds reach into a consumer segment that PromptPay alone does not fully cover.
Beyond PromptPay and TrueMoney, three additional wallets hold meaningful positions.
Rabbit LINE Pay integrates with Bangkok's BTS Skytrain system and the LINE messaging app. It bundles transit payments with micro-insurance and retail offers. Its user base skews urban and commuter-centric.
ShopeePay is the payment arm of Shopee, Southeast Asia's largest e-commerce platform. For merchants already selling on Shopee Thailand, ShopeePay integration is native to the platform.
GrabPay ties into Grab's ride-hailing and food delivery ecosystem. Grab Thailand's S.M.A.R.T. roadmap (announced April 2025) deepens the integration between rides, food, parcels, and GrabPay payments [2].
None of these wallets individually approach PromptPay's transaction volume, but together they represent the convenience layer that Thai consumers use for daily spending within specific ecosystems.
Thailand is at the center of Southeast Asia's cross-border QR payment network. PromptPay is now connected to more partner systems than any other national payment rail in the region.
The live cross-border connections include Singapore's PayNow (operational since April 2021, the first bilateral IPS link in ASEAN), Malaysia's DuitNow, Indonesia's QRIS, and Vietnam's VietQR [3]. A Thai tourist in Singapore can pay using PromptPay at any PayNow-accepting merchant. A Singaporean visiting Bangkok can pay with PayNow at PromptPay merchants.
Thailand is also a founding member of Project Nexus, the BIS-led multilateral platform linking real-time payment systems across Indonesia, Malaysia, Singapore, Thailand, the Philippines, and India. Project Nexus incorporated in Singapore in March 2025 and is expected to go live in 2026 [4].
For international businesses with customers or supply chains across ASEAN, these cross-border QR connections mean that a single Thai PromptPay integration increasingly enables acceptance of inbound payments from neighbouring countries. For the broader picture of how e-wallets work across Southeast Asia, including country-by-country breakdowns, see our SEA payments guide.
Three priorities for accepting payments in Thailand.
First, integrate PromptPay. This is the single most important payment method in Thailand. Without it, your checkout is inaccessible to the majority of Thai consumers. A payment gateway with PromptPay integration through National ITMX is the standard approach for international merchants.
Second, maintain card acceptance for higher-value transactions. Cards still account for a meaningful share of Thai e-commerce, particularly for international purchases, travel bookings, and premium goods. PromptPay and cards together cover the vast majority of Thai spending.
Third, consider TrueMoney for mass-market reach. If your business targets consumers outside Bangkok or in lower-income segments, TrueMoney's agent network provides cash-in capability that extends your addressable market beyond banked populations.
For businesses also paying out to Thai beneficiaries, Thailand is well-served by local rail payouts through PromptPay, with same-day settlement at significantly lower cost than SWIFT.
[1] Digital in Asia. "How Do Digital Payments Work in Southeast Asia in 2026?" June 2026. https://digitalinasia.com/how-digital-payments-work-in-southeast-asia/
[2] Mordor Intelligence. "Thailand Mobile Payments Market Report." January 2026. https://www.mordorintelligence.com/industry-reports/thailand-mobile-payments-market
[3] Digital in Asia. "State of Digital Payments Across Asia: A 15-Market Tracker." May 2026. https://digitalinasia.com/asia-digital-payments-tracker/
[4] BIS Innovation Hub. "Project Nexus: Enabling Instant Cross-Border Payments." https://www.bis.org/about/bisih/topics/fmis/nexus.htm
