Prepared by A-J | Author brand: 盡職生活｜阿J的普通人理財筆記
About the author/site · Vocus @WUCJ ↗ · Editorial policy
Page version: 2026-08-16 | Official or primary sources are preferred for material rules and figures. AI may assist structure, translation, and code, but is not used as the sole factual source.
About the author/site · Vocus @WUCJ ↗ · Editorial policy
Page version: 2026-08-16 | Official or primary sources are preferred for material rules and figures. AI may assist structure, translation, and code, but is not used as the sole factual source.
Key distinction: Market FX, a bank's posted rate, and your executable transaction rate can differ.
Bank buy means the bank buys foreign currency from you
If you hold U.S. dollars and convert them back to TWD, use the bank-buy rate.
Bank sell means the bank sells foreign currency to you
If you use TWD to buy U.S. dollars, use the bank-sell rate.
The sell rate is typically above the buy rate
The difference is part of the bid-ask spread and represents a cost of currency conversion.
Ask whether you are buying or selling foreign currency
Thinking from the bank's perspective prevents the most common reading error.
Primary / official sources
Posted rates change continuously. Actual transactions use the rate and fees shown by the executing bank, broker, or payment provider.