A wire from a US bank to Mexico does not touch SPID. The dollars get converted on the way and arrive as pesos.
SPID only matters when the dollars stay dollars and both accounts are already in Mexico. That one misunderstanding explains most of the confusion about how money moves inside the country, so it goes first.
This is for treasury, payments and product teams at fintechs, PSPs and remittance companies that hold or move dollars and pesos inside Mexico, and for anyone who wants to know exactly what happens between "I accepted the quote" and "the money is in the account."
SPEI vs SPID: hours, speed and who can use them
| SPEI | SPID | |
|---|---|---|
| Currency | Mexican pesos | US dollars, between accounts at Mexican banks |
| Run by | Banco de México | Banco de México |
| Hours | 24 hours, every day. Maintenance windows announced in advance. | Business days only, 08:00 to 14:15 Mexico City time |
| Speed | Seconds | Fast inside the window, but a bank can hold a payment until close of operations for anti-money-laundering checks. Miss the window and it moves the next business day. |
| Who can use it | Anyone with an account at a participating bank, via an 18-digit CLABE | Only companies domiciled in Mexico with a dollar account at a participating bank. No individuals. The bank needs the company's RFC and e.firma on file. |
| Who participates | Banks and other regulated institutions | Banks only. 29 commercial and development banks as of June 2026. |
| Central-bank liquidity | Yes, in pesos | None. Banks fund their dollar obligations through US correspondents. |
| What it is for | Payroll, suppliers, remittance payouts, any peso settlement | Moving dollars between Mexican dollar accounts without sending them abroad: paying a Mexican supplier in dollars, or funding or receiving the dollar side of an onshore FX trade |
What is SPEI and why does it settle pesos in seconds?
SPEI, the Sistema de Pagos Electrónicos Interbancarios, is Banco de México's real-time system for pesos. It clears transfers between banks in seconds, 24 hours a day, every day of the year. Every account is addressed by an 18-digit CLABE that encodes the bank, the branch and the account. Send to a wrong CLABE and the receiving bank rejects it and sends it back. It is a retry, not a loss.
For a treasury, SPEI means the peso side of any Mexico flow has no operational constraint worth planning around. Pesos can go out at 3am on a Sunday and arrive before you close the tab.
What is SPID and what is it for?
SPID, the Sistema de Pagos Interbancarios en Dólares, moves US dollars between dollar accounts at Mexican banks. It exists because Mexican companies hold dollar accounts onshore, mostly for import and export, and need to pay each other in dollars without routing the money through the United States and back.
It comes with four limits. It runs on business days only, 08:00 to 14:15. Only banks participate, and only Mexico-domiciled companies with a dollar account can use it. Banco de México provides no dollar liquidity, so each bank funds its SPID obligations with dollars held at a US correspondent. And even inside the window, a bank can hold a payment until close of operations to finish its anti-money-laundering checks.
In practice: a dollar payment between two Mexican accounts instructed on Friday afternoon moves on Monday, and a dollar deposit that lands after the cut-off is valued the next business day.
How an FX trade works with Rio: price, settlement and automatic payout
Rio works in a different order from a bank, and the order matters.
- Lock the price. You get a quote for the pair and the amount, all-in against the live market rate, with the market rate and the spread shown separately. Firm for the full amount for about ten seconds. Accept it and the trade is booked at that price. Piece 02 explains why the two numbers matter.
- Settle. You send Rio what you sold. Buying pesos: USDC or USDT to Rio's deposit address on the network of your choice, or dollars over SPID from your Mexican dollar account. Selling pesos: pesos over SPEI to Rio's account.
- Automatic payout. The moment your settlement lands, Rio pays out what you bought to the destination you whitelisted at onboarding: a CLABE for pesos over SPEI, a Mexican dollar account over SPID, or a wallet for USDC or USDT. No manual step. Seconds on SPEI and on-chain, inside the SPID window for dollars in Mexico.
Rio is not a direct participant in SPEI or SPID. It settles through its own accounts at regulated Mexican banks, which participate in both.
In Mexico, FX services are provided by Rampa Blockchain, S.A.P.I. de C.V., which performs operations with virtual assets as a vulnerable activity under Article 17, Section XVI of the LFPIORPI. Rio is a technology company, not a bank, and does not take deposits.
Four flows between dollars, pesos and stablecoins with one account
Because Rio sits on SPEI, SPID and the stablecoin networks at once, one account covers the combinations a Mexico treasury actually runs.
| From → to | Trade | You settle over | Rio pays out over | Hours |
|---|---|---|---|---|
| Dollars abroad → pesos in Mexico | USDC → MXN | On-chain | SPEI | 24/7 |
| Pesos in Mexico → dollars abroad | MXN → USDC | SPEI | Your whitelisted wallet | 24/7 |
| Dollars in Mexico → pesos in Mexico | USD → MXN | SPID | SPEI | Settlement inside the SPID window; payout instant once it arrives |
| Pesos in Mexico → dollars in Mexico | MXN → USD | SPEI | SPID | Payout inside the SPID window |
The first two never meet a banking cut-off. The first is the trade in Piece 01. The last two are for companies that keep dollar accounts onshore and want an FX price they can check against the market instead of taking the bank's, with the dollars staying in Mexico.
Which stablecoin network to settle on, and what changes between them
The FX price is the same on every network. Rio quotes against the market rate regardless of rail. What differs is how fast your settlement confirms and what the network fee is.
| Network | Stablecoins | Typical confirmation | Notes |
|---|---|---|---|
| Solana | USDC, USDT | Seconds | High throughput, very low fee. A common default for payment flows. |
| Arc | USDC | Under one second | Circle's own network, live since September 2026. Fees paid in USDC. Built for payment finality. |
| Stellar | USDC | Seconds | Very low fee. Widely used by remittance and payout networks. |
| Polygon | USDC, USDT | Seconds to a minute | Ethereum-compatible, low fee. |
| Tron | USDT | Seconds to a minute | The largest USDT network in emerging markets. |
| Ethereum | USDC, USDT | Minutes | Deepest liquidity for the tokens themselves, highest fee. |
| Base | USDC | Seconds to a minute | Ethereum-compatible, low fee. |
Most treasuries pick the network their counterparties already use rather than optimizing the leg. Whichever network your settlement arrives on, the payout that follows is identical. Addresses and network details are in the developer docs.
SPEI, SPID and stablecoins: what changes in a treasury's calendar
Keep the dollars inside the banking system and your Mexico flow runs on two clocks: business days for the dollar side, 24/7 for the peso side. Use stablecoins for the dollar side and both sides run 24/7. That is the difference between Friday afternoon conversions waiting for Monday or not, between weekend remittances funded at Friday's rate or Saturday's, and between scheduling your FX around the market or around your business. Piece 03 is about what the peso costs at each of those hours.
FAQ
What is a CLABE?
The Clave Bancaria Estandarizada, the 18-digit account number used for every SPEI transfer in Mexico. Three digits for the bank, three for the branch, eleven for the account, one check digit. A transfer to a CLABE that does not exist, or whose holder does not match, is rejected by the receiving bank and returned. A retry, not a loss.
Does a wire from the United States to Mexico go through SPID?
No. SPID only moves dollars between dollar accounts at Mexican banks, and only for companies domiciled in Mexico. A cross-border wire is converted to pesos by the banks along the way and lands in a Mexican peso account, from where it moves over SPEI.
Can Rio pay me in dollars inside Mexico?
Yes. If your company has a dollar account at a Mexican bank, you can trade pesos to dollars, settle the pesos over SPEI, and receive the dollars over SPID into the Mexican dollar account you whitelisted. The reverse works too: fund a dollars-to-pesos trade over SPID and receive pesos over SPEI. SPID payouts and funding are limited to business days, 08:00 to 14:15.
What happens if a SPID payment misses the cut-off?
It waits for the next business day. There is no after-hours window and no central-bank dollar liquidity in SPID. If you need the other side sooner, settle on-chain instead, which has no cut-off, or use Rio's overdraft so the payout goes today and you settle up to three days later.
What do I need to whitelist before trading?
The destinations Rio will pay out to: one or more CLABEs for pesos, a Mexican dollar account if you use SPID payouts, and a wallet address per network for USDC or USDT. Payouts only ever go to whitelisted destinations, which is what lets them run automatically the moment your settlement arrives.
What is Rio?
Rio is stablecoin FX infrastructure for Latin America. It provides liquidity, conversion and payout to local rails in Mexico, Colombia and Peru for fintechs and enterprises, with all-in pricing against the market rate, firm quotes for the full amount and settlement in minutes. Rio processes USD 12 billion in annualized volume.
In Mexico, FX services are provided by Rampa Blockchain, S.A.P.I. de C.V. Rio is a technology company, not a bank, and does not take deposits.
Related
Last updated: