A 90 percent hwanyul-udae (FX rate discount) at a Korean bank does not shave 90 percent off the exchange rate. It shaves 90 percent off the fee the bank adds on top of it. If the base rate is 1,400 won and the cash spread on US dollars is 1.75 percent, the unimproved buying rate is 1,424.5 won; with a 90 percent discount it is 1,402.45 won. Buying $1,000 costs 1,424,500 won instead of 1,402,450 won.
The saving is 22,050 won. The number 90 sounds dramatic, but against the principal it is a move from a 1.75 percent cost to a 0.18 percent cost. When comparing discount offers, the figure that matters is not the percentage itself but what that percentage is a percentage of.
What a 90% discount is actually discounting
A Korean bank's posted rate board lists three columns side by side: the base rate (maemae gijunyul), the cash buying rate, and the cash selling rate. The gap opening above and below the base rate is the FX fee, or spread. The Korea Federation of Banks consumer portal publishes this as the "foreign currency cash trading spread," noting that rates differ by currency because they reflect the cost of physically importing and holding banknotes.
The math is two lines. Applied spread = base spread x (1 - discount rate). Applied rate = base rate plus or minus the applied spread — plus when you buy, minus when you sell. KB Kookmin Bank's explainer works through a base rate of 1,200 won with the 1.75 percent dollar cash spread, producing 1,221 won to buy and 1,179 won to sell. Toss Bank defines a 100 percent discount as buying "at the price the bank itself paid for the currency — the base rate."
So the discount attaches to the bank's margin, not to the rate. The same 90 percent moves a lot of money on a wide-spread currency and almost none on a narrow one.
The discount is not a markdown on the exchange rate. It is a markdown on the bank's margin — and where the margin is thin, even 100 percent saves you little.
What each discount tier leaves you paying on $1,000
Assume a base rate of 1,400 won and a US dollar cash spread of 1.75 percent, or 24.5 won. The table below shows what buying $1,000 costs at each discount tier. The fee column is the actual won paid minus the base-rate equivalent of 1,400,000 won.
| Discount | Applied spread (KRW) | Buying rate (KRW) | Cost of $1,000 (KRW) | Fee paid (KRW) | Cost vs principal (%) |
|---|---|---|---|---|---|
| 0% | 24.50 | 1,424.50 | 1,424,500 | 24,500 | 1.75 |
| 50% | 12.25 | 1,412.25 | 1,412,250 | 12,250 | 0.88 |
| 80% | 4.90 | 1,404.90 | 1,404,900 | 4,900 | 0.35 |
| 90% | 2.45 | 1,402.45 | 1,402,450 | 2,450 | 0.18 |
| 100% | 0.00 | 1,400.00 | 1,400,000 | 0 | 0.00 |
The interesting stretch is between 80 and 90 percent. The headline number rises by ten points and the saving is 2,450 won — the price of a coffee on a $1,000 exchange. The first step from 0 to 50 percent, by contrast, removes 12,250 won on its own. The marketing battle fought in the high nineties is largely a battle over rounding.
Read the other way: the expensive scenario is exchanging a large sum in cash with no discount at all. Converting five million won at zero discount hands over 87,500 won in spread alone.
Buy and sell back, and 3.4% disappears
Currency exchange is often a round trip rather than a one-way move. Leftover cash from a trip gets converted back, and the spread is paid twice. Under the same assumptions, here is the round-trip loss on $1,000 bought and sold back with no movement in the rate itself.
| Discount | Buying rate (KRW) | Selling rate (KRW) | Round-trip loss (KRW) | vs purchase amount (%) |
|---|---|---|---|---|
| 0% | 1,424.50 | 1,375.50 | 49,000 | 3.44 |
| 50% | 1,412.25 | 1,387.75 | 24,500 | 1.74 |
| 90% | 1,402.45 | 1,397.55 | 4,900 | 0.35 |
| 100% | 1,400.00 | 1,400.00 | 0 | 0.00 |
With no discount, 3.44 percent of the principal evaporates without the rate moving a single won. Some advertised discounts apply only to the buying leg and not to selling or re-conversion — which means the second and third columns of this table can be computed at different discount rates. That is why the buying, selling, and re-conversion legs each need to be checked separately.
Cash at 1.75% and wire at 0.97% are different rates
Even for the same dollar, taking physical banknotes and moving money by wire carry different rates. On KB Kookmin's figures the dollar cash spread is 1.75 percent while the telegraphic transfer spread is 0.97 percent. The cost of flying banknotes in and holding them in a vault lands only on the cash side.
Applied to a 1,400 won base rate, that is 24,500 won per $1,000 in cash versus 13,580 won by wire — a gap of 10,920 won. Money destined for an overseas account or a foreign-currency deposit that gets converted into banknotes first and redeposited afterward simply throws that gap away. The same applies when weighing how FX gains on foreign-currency deposits are taxed differently from ETFs: the entry cost has to be identified as a cash rate or a wire rate before any return calculation holds up.
Why the discount ceiling differs by currency
Discounts are not applied uniformly across currencies. On KB Kookmin's published Foreign Currency Money Box terms, the ceiling is 90 percent for US dollars, 80 percent for Japanese yen and euros, 50 percent for Chinese yuan, British pounds, Canadian dollars and Australian dollars, and 20 percent for Malaysian ringgit, Vietnamese dong, Indonesian rupiah and Philippine peso.
The heavier the trading volume and the easier the banknote sourcing, the higher the ceiling. Thin-volume currencies get the opposite treatment — and since the base spread is also wider on those currencies, emerging-market money carries a double penalty: a bigger spread with a smaller discount applied to it. Whether it is cheaper to convert a Southeast Asia travel budget into local currency in Korea or to carry dollars and convert on arrival can only be answered by multiplying spread by discount along both routes.
What to watch
- Separate the legs the discount attaches to — buying, selling, and re-conversion can each carry a different rate.
- Check the base spread for your currency on the Korea Federation of Banks disclosure first. The discount is a multiplier applied to that number.
- Confirm whether you are quoted a cash rate or a wire rate. For dollars, 1.75 percent versus 0.97 percent is more than 10,000 won per $1,000.
- Look for caps. A discount limited per transaction, per day, or per year delivers a lower average discount on larger amounts.
- The gap between 90 and 100 percent is 2,450 won per $1,000. Convert that into cash before deciding a restrictive product is worth the paperwork.