Accepting payments in Mexico. 7 chapters and a final quiz.

Chapter 1. Three rails, three timelines, three customer bases.

Collecting payments in Mexico relies on three rails, each with its own settlement timeline and its own customers. A SPEI instant transfer credits the merchant without exposing the sale to a chargeback. Cards carry the average order once installments are offered. Convenience store counters reach buyers who have neither a card nor an account they can use online. These three groups barely overlap. A checkout that offers only two of the rails puts the buyers served by the third out of reach.

The decision rule in four questions

• Does the product ship immediately? If so, SPEI is the easy rail: irrevocable, no contracargo, credited in seconds. The cost falls on the buyer, who loses all protection against non-delivery. Your refund policy has to make up for that imbalance. Otherwise buyers won’t trust the rail and it won’t convert.
• Does the order value justify credit? Above the average order in your category, not offering meses sin intereses costs you conversion. In Mexico, installments are not a payment option. They are the credit product that makes the sale.
• What share of your target buyers pays cash? About one in two Mexican adults remains underbanked (Paypedia, Mexico country profile). Without an OXXO or Paynet reference, those buyers never enter your funnel. They don’t even show up as abandoned carts.
• Do you invoice from a Mexican entity? The answer drives everything else. Without registering with the RFC (Mexico’s federal taxpayer registry), you cannot issue a CFDI, and the local rails go through a partner. Chapter 7 walks through the three possible setups.

Chapter 2. SPEI and CLABE: wiring and reconciling transfers.

SPEI collection relies on a transfer pushed by the customer. The merchant debits no account. It displays a CLABE, the customer initiates the transfer from their banking app, and the funds arrive over a rail that has settled continuously under Banco de México’s responsibility since 2004. The integration challenge is reconciliation. The incoming credit carries the credited CLABE and an amount, plus a clave de rastreo (tracking key) generated by the payer’s bank when the transfer is initiated. None of these identifies the order, unless the CLABE itself is unique to that order.

// Repeating weights 3, 7, 1 applied to the first 17 digits.
// Keep only the ones digit of each product.
const WEIGHTS = [3, 7, 1]

function clabeCheckDigit(seventeenDigits) {
  let sum = 0
  for (let i = 0; i < 17; i++) {
    sum += (Number(seventeenDigits[i]) * WEIGHTS[i % 3]) % 10
  }
  return (10 - (sum % 10)) % 10
}

function isValidClabe(clabe) {
  if (!/^[0-9]{18}$/.test(clabe)) return false
  return clabeCheckDigit(clabe.slice(0, 17)) === Number(clabe[17])
}

// Test vector from the standard's public documentation:
// the first 17 digits of 032180000118359719 do yield 9.
isValidClabe("032180000118359719") // true

A virtual CLABE is an account key the provider assigns to a single order or a single customer. The credited key then identifies the order, and matching becomes deterministic. Without it, matching is done by hand, on amounts that look alike from one order to the next.

• SPEI has no direct debit mandate. Recurring payments go through cards or through domiciliación de recibos, run by Cecoban under a framework Banco de México has set since 2002. A subscription project that discovers this gap during acceptance testing loses a quarter.
• The payer controls the amount. They type in whatever they want. Write an underpayment policy and an overpayment policy before going live.
• Check who holds the account behind the CLABE: a bank, or an IFPE licensed by the CNBV (Mexico’s banking and securities regulator) under the 2018 Ley Fintech. Your customers’ funds are not protected the same way.
• Validate the check digit on the server. A mistyped CLABE costs a round trip with the customer and a complaint, never a silent error.
• Payee name verification is less mature than on the newest rails. For bulk outgoing payments, refunds included, add a check before execution.

Chapter 3. CoDi and DiMo: what to plug in and what to watch.

CoDi and DiMo are two initiation layers built on top of SPEI, launched in 2019 and 2023 respectively. CoDi has everything a modern rail needs, including free use and interoperability. Yet its use has remained marginal. DiMo’s user base is growing fast, but it mainly serves peer-to-peer transfers. The rail Mexican buyers already use to pay merchants is still the SPEI transfer.

DiMo hides the CLABE behind a mobile number without taking it out of the underlying rail. So the merchant’s data model still has to store a CLABE, validate it, and keep it for refunds. A mobile number carries neither the institution code nor the check digit.

Chapter 4. OXXO Pay and Paynet: the store counter as a payment terminal.

Cash payment at the counter relies on a barcode reference generated at checkout, which the customer shows at the register of a partner store. Hours, sometimes days, pass between the reference being generated and the cash being collected. The merchant has no control over that delay. Three business decisions come before the first line of code: how long the reference stays valid, whether to reserve stock, and what happens to an expired order.

• Validity period: configurable from a few hours to several days. A short window protects stock. A long one converts better. Test both before you commit.
• Upper and lower limits: at Conekta, the go-to operator for OXXO Pay, an order must be between MXN 15 and MXN 10,000 (Conekta help center, 2026). Above that cap, switch to SPEI.
• One unique reference per order, carried end to end, from checkout to the accounting entry. It is the only reliable matching key.
• Stock policy: on a rail that takes two days to confirm, reserving stock creates a stock-out risk, and not reserving it creates an overselling risk.
• A dedicated metric: the ratio of references generated to references paid. It is not the card authorization rate, and you manage it differently.

REFERENCE_ISSUED       (reference generated, expiry set)
   |-- payment -------> PAID         matched by reference
   |-- expiry --------> ABANDONED    sales follow-up, not a payment failure
   |-- cancellation --> CANCELED     by the customer or the merchant

PAID
   |-- shipment ------> SHIPPED
   |-- refund --------> REFUNDED     the refund does not go back through
                                     the counter: it needs a CLABE, so a
                                     field collected when it is requested

Classic trap: treating ABANDONED as a payment failure.
The card decline rate and the reference expiry rate do not
belong in the same metric.

Over-the-counter payment works as a customer acquisition channel in its own right. About one in two Mexican adults remains underbanked (Paypedia, Mexico country profile), and those people shop online. A reference paid in a store lets them pay for an online order without a card and without an account they can use remotely.

Chapter 5. Meses sin intereses: pricing the cost of deferral.

Meses sin intereses (literally “months without interest”) means splitting a card payment into interest-free installments. The merchant decides which plans to offer, one by one, in its acquiring contract. The customer pays the listed price in several monthly installments, with no interest or surcharge. The issuer advances the credit, and the merchant bears its cost as a deferral fee deducted from its settlement.

The tasa de descuento is the total fee a Mexican merchant pays on a card transaction, the local equivalent of the merchant discount rate. It breaks down into several parts: the cuota de intercambio (interchange fee) goes to the issuer, and the rest covers the network, switching, and the acquirer’s margin. Only that margin is truly negotiable. The other components depend on the regulatory cap, the networks’ fee schedules, and the switch the acquirer uses. Because the review of the caps began in November 2025, an acquiring contract signed in 2024 rests on a pre-reform framework.

// Enter the rates from YOUR acquiring contract and YOUR
// deferral table. Never decide an MSI plan on a market average.
const listPrice = 12000  // MXN, same shelf price paid upfront or with MSI
const goodsCost = 7800   // MXN

const tasaDescuento = 0 // your credit card rate, per your contract
const comisionMSI   = 0 // your deferral fee for the chosen plan

const netUpfront = listPrice * (1 - tasaDescuento)
const netWithMSI = listPrice * (1 - tasaDescuento - comisionMSI)

const marginUpfront = netUpfront - goodsCost
const marginWithMSI = netWithMSI - goodsCost

// planCost = what installments cost you on this sale.
const planCost = marginUpfront - marginWithMSI

// The only question that matters: does the lift in order value and
// conversion measured on this plan cover planCost? Without measurement,
// the plan is chosen blind and renewed out of habit.

• Insist on the full deferral table, plan by plan, before signing. A partial schedule makes the cost unpredictable.
• Offer plans by order-value tier, not across the whole catalog. A 12-installment plan on a MXN 500 order destroys the margin and gains nothing.
• Ask for the observed debit-credit mix in your sector: the MXN 13.50 cap on debit changes the economics of large orders.
• Measure the order-value lift plan by plan, not overall. It is the only number that justifies keeping a plan open.
• Put a date on your terms. The cuotas de intercambio framework has been under review since November 2025; a clause indexing your rates to the regulatory caps is easier to negotiate before the reform than after.

Chapter 6. CFDI 4.0: the invoice that completes the sale.

The CFDI (Comprobante Fiscal Digital por Internet) is Mexico’s mandatory electronic invoice, established by Articles 29 and 29-A of the Código Fiscal de la Federación. The current version is 4.0. For tax purposes, a sale is only complete at timbrado (stamping), the step in which an authorized provider applies the seal of the SAT (Mexico’s tax authority) to the invoice XML. An unstamped XML has no tax validity for either the issuer or the recipient.

• Generic RFC: XAXX010101000 for a Mexican buyer who does not provide an RFC, XEXX010101000 for a foreign resident (SAT catalogs).
• Factura global: the CFDI that consolidates sales to the público en general (general public) over a period. Recipient name PUBLICO EN GENERAL in capital letters, tax regime 616 (Sin obligaciones fiscales), uso S01 (Sin efectos fiscales).
• Frequency: the factura global is issued for a closed period and includes only transactions paid under PUE. A deferred payment does not go in it.
• Self-invoicing: a customer can request an invoice in their own name after the purchase. Plan for the portal, and for the rule that removes that line from the factura global.

Canceling a stamped CFDI follows a dedicated procedure that requires a reason code from the SAT catalog. There are four reasons: an error with a replacement invoice, an error without replacement, a transaction that did not take place, and a named transaction already included in a factura global. The recipient must accept the cancellation in the cases the rules specify. Build this flow before the first sale, because an incorrect invoice remains legally binding until it is canceled.

Chapter 7. Mexican acquirers, declines, and fraud.

The authorization rate on a card transaction in Mexico depends first on where it is acquired. A Mexican issuer does not treat a transaction acquired in Mexico the same way as one acquired abroad. No tuning of the merchant’s fraud engine closes that gap, because the authorization decision belongs to the issuer. The lever is the acquiring setup you choose, and the switch it routes through.

• Acquire domestically as soon as volume justifies it. It is the only structural fix for cross-border declines; no fraud-rule tuning can replace it.
• Separate hard declines from soft declines in your dashboards. Retrying a 05 over and over damages your standing with the issuer.
• Offer an alternative rail the moment a card is declined: a CLABE or an OXXO reference recovers some of the orders an error message loses for good.
• Track authorization by issuer, by BIN, and by amount band. The national average hides exactly what you need to fix.
• Document the aclaración process: in Mexico, cardholders dispute with their issuer first. You must be able to produce your proof of delivery and your CEPs within 48 hours.