The ISA (Individual Savings Account) is a Korean government-designed account offering tax advantages to encourage saving and investing. Ads often describe it as a "tax-free account," but what does the actual tax benefit look like? This article breaks down ISA's real value for a salaried worker using concrete numbers.
ISA Tax Benefits — Two Core Rules
- Tax-free threshold: 2M KRW for general accounts, 4M KRW for lower-income workers (total income ≤ 50M KRW). All gains from interest, dividends, and capital gains within this limit are completely tax-free.
- 9.9% separate taxation on amounts above the threshold: Instead of the standard 15.4% withholding tax, only 9.9% applies to gains above the tax-free limit. These gains are also excluded from comprehensive income, avoiding progressive tax bracket creep.
Regular Account vs. ISA — Same Return, Different Result
Scenario: 300K KRW/month for 5 years, 6% annual return.
- Total principal: 18M KRW
- Value after 5 years (compound): ~21.07M KRW
- Total gain: ~3.07M KRW
Regular account (15.4% withholding): 3.07M × 15.4% = ~470K KRW in taxes → 2.6M KRW net gain
ISA general account (2M free + 9.9%):
- First 2M KRW: 0 tax
- Remaining 1.07M × 9.9% = ~106K KRW in taxes
- Total tax: 106K KRW → 2.96M KRW net gain
With the same 5-year timeline and return rate, ISA leaves you roughly 360K KRW more. That's about 78% less tax paid compared to a regular account. The advantage scales proportionally as the amounts grow.
ISA Gotchas — Know These Before You Open One
- 3-year mandatory holding period: Withdraw before 3 years and all tax benefits are clawed back. Never put money in ISA that you might need urgently.
- Annual contribution cap: 20M KRW: Up to 100M KRW over 5 years. High-net-worth investors will find this insufficient.
- No direct U.S. stock purchases: You can't buy U.S. stocks directly inside ISA. Workaround: invest via Korean-listed U.S. ETFs (TIGER, KODEX, ACE).
- Brokerage vs. trust vs. discretionary accounts: Brokerage-type (중개형) gives the most flexibility. Trust-type is through banks; discretionary-type is managed by an asset manager.
Transferring to IRP After Maturity — The Real Tax Magic
After the ISA matures (3+ years), transferring funds to an IRP (Individual Retirement Pension) unlocks an additional benefit:
- 10% of the transferred amount (up to 3M KRW) is added to your IRP tax deduction limit
- Example: Transfer 30M KRW from ISA to IRP → 3M KRW extra tax deduction limit → ~490K KRW extra tax refund
- Note: IRP funds are locked until age 55, so this strategy is best suited for retirement savings.
Who Should Use ISA?
- ✅ Salaried workers who can lock up funds for 3+ years
- ✅ Higher-income earners in progressive tax brackets (separate taxation saves money)
- ✅ People in their 30s–50s wanting both retirement planning and tax savings
- ❌ Recent graduates expecting major spending soon (marriage, moving, etc.) — the 3-year lock is a real constraint
- ❌ Investors whose core strategy requires buying U.S. stocks directly
Quick Start Guide
- Open a "중개형 ISA" (brokerage-type ISA) on any securities app — takes about 5 minutes
- Set up a monthly automatic transfer (as low as 100K KRW/month)
- Buy Korean-listed ETFs (TIGER S&P500, KODEX 200, ACE NASDAQ100, etc.)
- When the account matures after 3 years, consider rolling over to IRP for the additional tax deduction
Calculate Your Own Tax Savings
Want to compare a regular account vs. ISA using your own contribution amount, period, and return rate? Try the compound interest calculator and change the tax rate from 15.4% (regular) to 9.9% (ISA above-threshold).
Compare with Compound Calculator →
ISA tax benefits are subject to change based on government policy. Verify the latest tax regulations and your personal tax bracket with a tax advisor or financial professional before opening an account.