The 1-Won Deposit Check: How Apps Verify Your Bank Account in Korea

If you've ever linked a bank account to a payment app for the first time, you may have seen 1 won show up in your account. The point isn't the money. It's the secret code in the sender name that comes with it.

A service needs a way to tell whether someone who knows an account number is the real owner. Account numbers are easy to expose, on receipts or on online message boards. So the company sends 1 won to that account and quietly puts a random number or word where the sender's name would go.

Deposit history is normally visible only through channels the account owner receives, like the bank's app or a deposit alert text. So if you can read the secret code and type it correctly into the verification screen, that shows you can see that account's deposit history. That's how the check works.

Behind this short check, financial networks and software interfaces are working nonstop. When you enter your bank and account number, the company's server sends an instant 1-won transfer order to your bank. It goes through the Korea Financial Telecommunications and Clearings Institute (KFTC) network or Korea's Open Banking system.

Each transfer carries a one-time code that is newly generated every time, in the memo. The whole thing runs through agreed-upon data exchange between computer programs, so it's usually done automatically within a few seconds (it can be slower during bank maintenance windows).

To be more precise, the company doesn't have staff at every bank sending money by hand. It uses electronic channels connected to the banks' shared financial network, and handles large volumes of account-holder name lookups and 1-won transfers with a real-time automated system.

In the past, proving your bank account online meant submitting a photo of your ID or visiting a bank branch in person. But a copy of an ID alone can still be stolen or forged. So for remote account opening, companies usually combine an ID copy check with an existing-account check like the 1-won transfer, which lowers the risk of identity theft.

The 1-won check uses an account you already created by passing the bank's strict real-name verification. In effect, it borrows the strong security the bank has already built. In some cases, such as linking an account to a payment app like Apple Pay, an account can be confirmed with just the account-holder name lookup and the 1-won check, with no ID at all.

The 1 won that moves around costs almost nothing, yet it makes identity theft harder. Even if someone steals another person's account number and tries to link it to a payment service, it's hard to get through without being able to see the deposit alert or the account's transaction history. That said, some scammers trick victims into reading out the code shown in the sender name and hijack the check, so this method alone can't fully stop identity theft.