Banco de México's exchange-rate table separates the FIX rate from the rate published in Mexico's official gazette and the rate applicable for payment. The three columns can carry different numbers on the same displayed date. Understanding that calendar is essential when a payment or contract refers to the official benchmark. Banco de México — exchange rate for US-dollar obligations payable in Mexico, table and explanatory notes ↗
Start with the benchmark's determination
The immediate task is to identify the rule governing the obligation and the relevant banking day. Selecting the newest-looking number on a screen is an unreliable substitute for that process.
Banco de México says it determines FIX on banking days using an average of wholesale foreign-exchange quotations for operations settling on the second banking day after determination. It announces the rate from noon onwards on the determination day. Publication in the Diario Oficial de la Federación follows on the next banking day. Banco de México — exchange rate for US-dollar obligations payable in Mexico, table and explanatory notes ↗
The central bank's historical explanation describes the further timing link for dollar-denominated obligations payable in Mexico: the applicable rate follows the official-gazette publication schedule. It also notes that private contracting parties may agree on another exchange rate. The actual agreement and applicable rules therefore remain necessary to identify the correct input. Banco de México — Exchange Rate Regimes in Mexico since 1954 ↗
This is a benchmark and payment-timing framework. A separate bank conversion, card payment or trading-platform transaction may have its own executable rate, spread and charges.
Read a real table row across all three columns
For 16 October 2026, the central bank's table showed a FIX determination of 18.4930 pesos per dollar, an official-gazette publication value of 18.4250 and a payment value of 18.4888. These are the values displayed for that dated row when checked on 19 October. Their coexistence reflects the table's timing conventions rather than three simultaneous executable quotes. Banco de México — exchange rate for US-dollar obligations payable in Mexico, table and explanatory notes ↗
For illustration only, applying the row's payment value to a USD10,000 obligation produces MXN184,888. Applying its FIX determination value instead produces MXN184,930, a difference of MXN42. This arithmetic isolates the effect of choosing the column; it excludes fees, rounding rules in a particular agreement and any separate conversion transaction.
Store the dates alongside the rate
A reproducible calculation needs the obligation's currency and amount, its payment date, the chosen official series or contractual benchmark, the relevant published value and the conversion direction. Keeping only a number labelled today's dollar leaves too much unidentified.
Banking holidays also make calendar-day shortcuts fragile. A process that simply subtracts one date from another can point to a day on which the relevant series was not determined or published. The central bank's table and its banking-day notes should guide the date mapping. Banco de México — exchange rate for US-dollar obligations payable in Mexico, table and explanatory notes ↗
For treasury and brokerage teams, an appropriate reconciliation record preserves the source row used at the time of calculation. A later change in the live market does not rewrite that historical input. With the payment rule and observation date documented, another reviewer can reproduce the peso amount and explain why it differs from a contemporaneous trading quote.