What This Calculator Does and Doesn't Do

It applies the same principal, period, and assumed return to three paths — direct investing, Pension Savings/IRP, and ISA — and computes what's left after tax in each. Pension Savings/IRP assumes even annual contributions and shows the tax-deduction refund separately (so it doesn't get mixed up with the tax charged on withdrawal). The rules used (rates, thresholds, age bands) are as of 2026 — see Investing in US Stocks via Pension and ISA Accounts for a fuller explanation of the account types themselves.

This is not individual advice. Your actual result depends on your income bracket, existing contributions, other income, and withdrawal timing, and we do not recommend any specific brokerage or product. Confirm actual filing and deductions via Korea's National Tax Service (Hometax) or a tax professional. Results are an approximation for reference and do not substitute for tax consultation. For a detailed direct-investing capital-gains calculation alone, use the overseas stock tax calculator.

Rules like tax rates, deduction limits, and age bands can be revised annually, so we keep them in a single constants file (the rules SSOT) and use those values directly in this calculation. We left out details we weren't confident about — where a rule was ambiguous, we decided it was better to say "confirm with the National Tax Service" than to guess convincingly. Pension Savings/IRP assumes even annual contributions, so if your actual contributions varied year to year, the total tax-deduction figure here may differ from reality.

Worked Example

Example (an illustrative assumption — not a return prediction): growing a 30,000,000-won principal for 10 years at an assumed 7% annual return, with a low income bracket (annual salary ≤55,000,000 won), withdrawal at age 60, and a general-type ISA, produces a pre-tax value of 59,014,541 won (a gain of 29,014,541 won). Direct investing subtracts the 2,500,000-won basic deduction to get a 26,514,541-won taxable base, taxed at 22%, leaving 53,181,342 won after tax. Pension Savings/IRP separately refunds 4,950,000 won in tax credits over the contribution period, and a normal withdrawal at 60 is taxed at the 5.5% pension-income rate, leaving 55,768,741 won after tax. Under the same assumptions, an early/disqualified withdrawal (e.g., before age 55) is taxed at 16.5% instead, leaving only 49,277,142 won. A general-type ISA taxes only the gain above its 2,000,000-won tax-free threshold at 9.9%, leaving 56,340,101 won after tax.

What's Included and Excluded

Included: computing direct investing, Pension Savings/IRP, and ISA side by side under the same principal, period, and assumed return; showing Pension Savings/IRP's annual tax-credit refund separately from the tax charged at withdrawal; calculating both a normal withdrawal (age-banded pension-income tax) and an early-withdrawal scenario (the less favorable rate); and applying ISA's different tax-free thresholds by income type (general vs. low-income).
Excluded: actual product fees for a specific pension product, accumulated error in the tax-credit total when annual contributions are uneven, offsetting gains and losses across multiple trades within the direct-investing path, reinvestment or combined taxation with other income after withdrawal, and whether the principal/return figures are meant in real (inflation-adjusted) or nominal terms.

Reading the Result

The "after-tax amount" is what the calculation produces if your assumed return is realized exactly as entered — it is not a conclusion that any one path is always better. Pension Savings/IRP showing a higher after-tax figure than another path reflects the added tax-credit refund, not better investment performance itself. If the withdrawal age is under 55, the result shows as "does not meet withdrawal requirements," and no normal-withdrawal tax or after-tax amount is computed (only the early-withdrawal-rate scenario is calculated separately) — this is not a bug; it reflects that the qualifying age for normal pension withdrawal is 55 under the actual rules.

Out-of-Range Inputs

Principal outside 1,000,000–2,000,000,000 won, a period outside 1–40 years, an assumed return outside −20% to 30%, or a withdrawal age outside 30–100 each triggers its own error: "Check the investment principal range," "Check the investment period range," "Check the assumed return range," or "Check the withdrawal age range," respectively. An income bracket other than low/high, or an ISA type other than general/low-income, triggers "Check the income bracket value" or "Check the ISA type value."

Assumptions and Limits — Rules Applied (as of 2026)

Direct investing: a 2,500,000-won basic deduction and a 22% rate. Pension Savings/IRP: a 16.5% tax-credit rate (annual salary ≤55,000,000 won) or 13.2% (above), and pension-income tax of 5.5% (age 55–70), 4.4% (70–80), or 3.3% (80+), with a 16.5% rate for early or disqualified withdrawal. ISA: a tax-free threshold of 2,000,000 won (general) or 4,000,000 won (low-income), with 9.9% on the amount above it. All of these are 2026 tax-rule figures, are subject to annual revision, and should be reconfirmed via Korea's National Tax Service (Hometax) or a tax professional at the actual time of filing or withdrawal.