Savings Interest Calculator

Smart Savings: Interest Calculation and Financial Strategies

Deposits and installment savings remain the safest way to build seed money. But focusing only on headline rates can cause you to overlook the after-tax interest you actually receive. Use this calculator to understand your real returns and build a more effective wealth plan.

1. Time deposits vs installment savings

• Time Deposit: A lump sum deposited at once and held until maturity. Best for growing existing funds.
• Installment Savings: Monthly contributions over a set period. Ideal for building up capital from scratch.

Note that even if installment savings offer a higher rate, actual interest may be lower because later deposits earn interest for fewer months. The effective yield is roughly half the stated rate.

2. Interest income tax

15.4% (14% income tax + 1.4% local tax) is withheld on interest income. On KRW 100,000 of interest, you receive only KRW 84,600. Tax-exempt savings, credit union preferential rates, and ISA accounts can help maximize returns.

3. Simple vs compound interest

Most Korean savings products use simple interest, but reinvesting maturity interest creates a compound effect over time. Even a 0.1% rate difference compounds significantly over the long term.

4. Inflation and savings

Savings are principal-protected but if inflation exceeds the interest rate, your real purchasing power decreases. Diversify part of your assets into equities, bonds, or gold to hedge against inflation.