You estimate the interest on a Korean bank deposit, then receive less at maturity than expected. The first thing to check is whether the estimate showed pre-tax interest while the bank paid the amount left after withholding. The product’s dates and conditions can matter, too.
Check pre-tax and after-tax amounts
Pre-tax interest is earned before withholding; the maturity amount is what is credited after applicable tax. South Korea’s National Tax Service lists a 14% withholding rate for general interest income, but tax-advantaged accounts and personal circumstances can change what applies. Confirm the treatment for your account rather than assuming one rate fits everyone. See the National Tax Service guidance and Article 129 of Korea’s Income Tax Act.
A bank app may show an estimate based on assumptions, including a promotional rate you may not qualify for. Check the applied rate, tax treatment, and expected maturity amount in the product details.
The deposit period is more than “one year”
Actual start and maturity dates, leap years, and the day-count method in the terms can change the calculation. A single online formula will not match every product. Installment savings work differently from a lump-sum deposit: each monthly payment earns interest for a different length of time. The first payment stays in the account longest; the last stays for the shortest time.
Promotional rates have conditions
A headline rate may include bonuses for salary deposits, card use, automatic transfers, or new-customer status. Check whether you met the conditions and how broadly the bonus applies. Early closure may replace the agreed rate with a lower early-termination rate; the terms also explain what happens when maturity falls on a holiday and when interest is paid.
A quick check before maturity
In your bank app, confirm the amounts and dates deposited, the base and bonus rates actually applied, whether the estimate is before or after tax, and the maturity amount. If it still differs, ask the bank which dates and rate it used.
Deposit interest is not determined by the advertised rate alone. It depends on how much was deposited, how long each payment stayed in the account, the conditions met, the product’s calculation method, and applicable tax. Compare the amount you are likely to receive—not only the largest rate in the headline.