Benchmark fix or live quote: which exchange rate should your payouts use?

Use a benchmark fix for contracts, valuation, and reporting, and a live quote for the payout itself. A fix such as WM/R 4 p.m., PTAX, Banxico's FIX, or the ECB reference rate is an average of a past window. A live quote is an executable price for your amount right now. Most teams need both.

The confusion shows up at payment time. A supplier invoice says "converted at PTAX," the payout quote says something else, and someone asks which one is right. Both are. They answer different questions. How on/off-ramp providers make money explains the margin inside a quote; this page explains how a benchmark relates to it.

Key takeaways

• A fix is a benchmark computed from a past window. You can reference it, but nobody fills your payout at it by default.
• A live quote is executable: your amount, this minute, spread and fees included.
• Contracts and accounting use fixes because everyone can look up the same number.
• Payouts use live quotes because the money moves at a market price, not at yesterday's average.
• Bridge the two with a receiver-side quote: let the fix set the local amount and the live quote deliver it.
• Split any gap into market movement and execution cost, so you know which one to question.

What are the main FX fixes?

Four benchmarks cover most payout corridors. Each has an administrator, a window, and a publication time, and none of them is a price you can trade at after it prints. Knowing which one a contract names, and when it was calculated, is the first step to explaining any gap.

Sources for each row: the WMR FX Benchmarks fact sheet, which lists uses from "Settling financial contracts" to "Valuation of investment funds"; BCB's open data portal for PTAX; Banxico's FIX page; and the ECB reference rates page.

The ECB is blunt about its own rates: "Using the rates for transaction purposes is strongly discouraged." That sentence applies in spirit to every fix on the list.

Why can't a payout simply execute at the fix?

Because a fix is published after its window closes, and the market keeps moving. To fill you at the fix, someone has to trade during the window and take the risk that their trades differ from the average. That service exists in wholesale FX, as a fixing order, but it is not the default for a payout.

Three practical reasons a payout uses a live price instead:

1. Timing. Banxico releases FIX from 12:00, and the ECB updates its rates around 16:00 CET. A payout sent at another hour happens at another market price.
2. Size and cost. A fix is a market average, often a mid rate. Your payout pays a spread and fees on your amount. Those are real costs, and a fix leaves them out.
3. Crowding. Large orders tied to a fix bunch into the same minutes. That concentration is exactly why benchmark windows and conduct rules exist around them.

So the honest framing is: the fix tells you what the market averaged; the quote tells you what your payout will cost.

When is a fix the right rate to use?

When many parties need to agree on one number after the fact. Contracts, tax calculations, financial statements, and month-end valuations all need a rate anyone can look up later and get the same answer. A fix does that. A live quote, timestamped to one minute for one amount, does not.

Use a fix for:

• Contract pricing. "The BRL amount equals the USD invoice times PTAX on the invoice date." Both sides can verify it.
• Obligations under local rules. In Mexico, the rate for dollar obligations payable in Mexico is the FIX published in the Diario Oficial on the banking day before, per Banxico.
• Valuation and reporting. A treasury holding USDC and paying in reais can mark balances at one named fix per day.
• Benchmarking a provider. Compare a month of executed rates with the fix to see the trend, as long as you account for timing.

Which reference rate a finance team should use covers the reporting choice in short form.

When does a payout need a live quote?

Every time money actually moves. A live quote is the price at which your specific payout executes: amount, corridor, rail, network, fees, and a window to accept it. It is the only number that tells you exactly what leaves your wallet and what lands in the recipient's account.

BlindPay prices every payout this way. A payout quote returns commercial_quotation, the raw market rate when the quote was created, and blindpay_quotation, the rate net of BlindPay's fee, plus sender_amount and receiver_amount. It locks those numbers for 5 minutes; read expires_at on every response (payout quotes docs). Fees vary by rail and network and are disclosed in the live quote before execute.

If you need a rate held longer than a quote window, that is a different product. Live quote vs forward contract vs fixed rate explains when a forward fits.

How do you pay a contract priced at a fix?

Let the fix set the local amount, then use a receiver-side live quote to deliver exactly that amount. The supplier gets what the contract says. Your stablecoin cost moves with the market and the quote. The difference from the fix-implied cost is yours to track, split into movement and execution.

On BlindPay, currency_type: "receiver" makes request_amount the fiat amount the bank account receives, so the quote solves for the stablecoin you send (payout quotes docs).

Illustrative example. A supplier invoice of R$ 540,000 was priced at PTAX 5.40 on the invoice date, an implied cost of 100,000 USD. On payment day the mid-market rate is 5.38, and the live receiver-side quote rate is 5.37 BRL per USDC.

Of the 558.66 USDC gap, two thirds is market movement, which no provider controls. One third is the cost of execution, which is the part to compare across providers. These are illustrative numbers, not BlindPay pricing.

How should your FX policy name both rates?

Name one fix per reporting job and one rule for execution. Write which benchmark marks balances at month end, which one contracts reference, and that payouts execute on live quotes captured with a mid-market reference at the same minute. Then no one argues about it in the close.

A short version:

1. Valuation: stablecoin balances marked at a named daily fix, for example WM/R 4 p.m.
2. Contracts in BRL or MXN: local amount set by PTAX or FIX on a named date.
3. Execution: every payout on a live quote, with the quote record stored.
4. Variance reporting: gap to the fix split into movement and execution cost, monthly.
5. Timing: payouts tied to a fix go out on a set schedule, so movement doesn't pile up.

Best execution for stablecoin payouts covers the records that make the execution line defensible.

What to do next

Pick one contract that names PTAX or FIX. On a BlindPay development instance, create a receiver-side quote for its local amount, record commercial_quotation, and run the movement and execution split above. The payout quotes docs explain currency_type.