Korea Savings Interest Calculator
Last updated: 2026-06-25
Simple installment savings interest = monthly deposit × monthly rate × (months × (months+1) ÷ 2), where monthly rate = annual rate ÷ 12.
Korean savings and deposit interest is taxed at 15.4%, so after-tax maturity = principal + pre-tax interest × (1 − 0.154).
Enter savings / deposit details
After-tax maturity amount
0 KRW
How to use
- Choose product — Choose installment savings (monthly deposit) or a lump-sum deposit.
- Enter amount, rate and term — Enter the monthly deposit (or principal), annual rate (%) and term (months). For deposits you can choose simple or compound.
- View the result — The pre-tax interest, 15.4% interest income tax, after-tax maturity amount and principal are shown.
How savings and deposit interest is calculated
Installment savings is paid in a fixed amount each month, while a deposit places a lump sum at the start. Because each savings installment is held for a different length of time, savings earns less interest than a deposit at the same rate.
| Product | Formula (pre-tax interest) |
|---|---|
| Savings (simple) | Monthly deposit × monthly rate × (n × (n+1) ÷ 2), monthly rate = annual rate ÷ 12 |
| Deposit (simple) | Principal × annual rate × (months ÷ 12) |
| Deposit (monthly compound) | Principal × (1 + annual rate ÷ 12)months − Principal |
All products have 15.4% withheld on interest (14% interest income tax plus 1.4% local income tax). So after-tax interest is the pre-tax interest minus 15.4%, and the after-tax maturity amount is the principal plus after-tax interest.
Frequently asked questions (FAQ)
How is installment savings interest calculated?
Simple installment savings interest = monthly deposit x monthly rate x (months x (months+1) / 2). The monthly rate is the annual rate divided by 12. Because each monthly deposit stays for a different length of time, earlier deposits earn more interest.
Why is savings interest different from deposit interest?
A lump-sum deposit earns interest on the full amount for the whole period, while installment savings is paid in monthly so its average holding period is about half. For the same rate and total amount, savings interest is about half of deposit interest.
How much is the interest income tax?
Interest from savings and deposits is subject to 15.4% withholding (14% interest income tax plus 1.4% local income tax). The after-tax interest is the pre-tax interest minus this 15.4%.
How do simple and compound interest differ?
Simple interest applies only to the principal, while compound interest also applies to interest already earned. The longer the term, the larger compound interest grows over simple. This calculator supports both simple and monthly-compound for deposits.
What is the difference between pre-tax interest and the after-tax amount?
Pre-tax interest is the interest before tax, while the after-tax amount is the principal plus after-tax interest (pre-tax interest minus 15.4% tax) at maturity. The amount actually deposited to your account is the after-tax maturity amount.
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Last updated: 2026-06-25