Savings & Deposit Maturity Calculator
Enter your monthly contribution (or lump-sum deposit), period, and rate to compute the maturity value with simple or monthly compounding. The 15.4% interest income tax is auto-deducted.
Fixed amount auto-debited each month for the full period.
Use the bank's quoted nominal rate (e.g., 4.0).
Maturity amount (after tax)
6,109,980KRW
After-tax yield on principal: 1.83%
- Principal
- 6,000,000KRW
- Pre-tax interest
- 130,000KRW
- Interest tax
- 20,020KRW15.4%
- After-tax interest
- 109,980KRW
- Simple-interest method applied
- Interest tax 15.4% withheld
What is maturity value?
Recurring savings (적금) auto-debit a fixed monthly amount and pay back principal + interest at maturity. Time deposits (정기예금) lock a lump sum until maturity for principal + interest. Interest can be simple (only on principal) or monthly compounded (interest earns interest). Korean recurring savings are typically simple; some products offer monthly compounding. Earned interest is subject to a 14% income tax + 1.4% local tax, totaling 15.4%, withheld at source. Tax-exempt accounts (qualifying seniors, low-income, etc.) skip the withholding within their cap.
Formulas
Recurring simple interest = M × r × n(n+1) / (2 × 12)
Recurring compound future value = M × ((1+i)^n − 1) / i × (1+i), i = r/12
Deposit simple interest = P × r × n / 12
Deposit compound future value = P × (1 + r/12)^n
After-tax interest = pre-tax interest × (1 − 15.4%)
Frequently asked questions
- Is it always 15.4%?
- Standard accounts withhold 14% + 1.4% local = 15.4%. Tax-exempt savings (limited to seniors, registered disabilities, basic livelihood recipients) are exempt within their cap. The legacy 9.5% favorable-tax savings program no longer accepts new enrollments.
- Why is recurring simple-interest divided by 12?
- The annual rate is converted to monthly. The first month's deposit accrues for n months while the last accrues for 1 month — average (n+1)/2 months. Total = monthly × annual rate × n(n+1)/2 / 12.
- How much more does compounding give?
- Small at short tenor or low rates; meaningful at longer tenor and higher rates. A 5-year, 10M KRW, 4% deposit yields about 2.0M (simple) vs 2.21M (monthly compound).
- Why might my actual receipt differ?
- Promo rates (auto-debit, card use, referrals) can boost the rate. Early termination uses a much lower 'mid-cancel' rate. This calculator uses the contracted rate only.
Reference only — uses the contracted rate. Promo rates, mid-cancel penalties, tax-exempt or favorable-tax caps, daily/yearly compounding, and auto-rollover are not modeled. Confirm the precise maturity amount in your bank's mobile app or branch.