The short version: A guaranteed exchange rate is conditional. The rate, expiry time and funding requirement belong together; a screenshot of the rate alone is an incomplete record.
Read what makes the guarantee effective
Wise’s help page distinguishes payment methods: for a connected bank account paid through ACH, it describes the lock as taking effect when payment is authorized; for other methods, it requires the full amount to arrive before the deadline. It also describes loss of the guarantee for partial funding and use of the live rate when funds arrive after expiry. These are Wise’s published conditions, not a universal rule for transfer providers.
The operational question is therefore specific: does the deadline refer to your authorization, your bank sending the payment, or the provider receiving all the funds? A bank confirmation may prove the first step without proving the last.
What a one-cent rate change means
Hypothetical worked example—not a live quote. Take $1,000 of principal and ignore fees solely to isolate the rate effect. At a locked €0.90 per dollar, conversion produces €900. If that lock expires and the applicable rate becomes €0.89, conversion produces €890.
| Assumed conversion rate | Calculation | Before-fee result |
|---|---|---|
| €0.90 per $1 | $1,000 × 0.90 | €900 |
| €0.89 per $1 | $1,000 × 0.89 | €890 |
| Difference | €900 − €890 | €10 |
The €10 difference is not a separately invoiced fee in this example. It is the effect of using a different rate. If the later rate instead became €0.91, the result would be €910 before fees. Neither direction is assured.
A partial payment is not automatically a partial guarantee
Suppose a transfer requires $1,000 but only $600 reaches the provider before the deadline. It would be unsafe to assume that $600 receives the locked rate and only $400 receives a later rate. That split is a separate contractual rule; it does not follow from multiplication. Wise’s cited guidance says partial funding does not preserve the guarantee unless the transfer is adjusted or the remainder arrives within its conditions.
Keep a complete quote record
Record the sending and receiving currencies, principal, fee treatment, rate, deadline and displayed time zone, funding method, and the event that must occur by the deadline. Also retain any actual arrival or authorization confirmation. These details make it possible to explain a difference later without guessing which rate applied.
A rate lock does not by itself promise a recipient delivery time or remove recipient deductions. Check those terms separately. It also does not make one provider cheapest: compare the full recipient outcome and total debit using the same assumptions, as described in our methodology. This article explains a condition to verify, not a market-timing strategy.
Source and scope
Primary source: Wise Help Centre, guaranteed rates. Accessed 22 October 2026. The numerical examples are independently constructed teaching examples, not provider prices. Product terms and rules can change; check the terms that apply to your transaction.
This article is financial education, not personal financial advice or a product recommendation. It contains no paid links. See our disclaimer.
