ISA Calculator
Compare ISA gains, tax treatment, and after-tax outcomes for stock, ETF, bond, RP, and deposit-income scenarios.
ISA scenario
Choose account and asset branches, then calculate trade or dividend flow in separate tabs.
Common stock or sale inputs
Foreign assets use the exchange-rate field for a simple KRW conversion.
Used for foreign stock and foreign ETF branches.
20M KRW
ISA outcome comparison
Gains, taxes, and after-tax values are shown side by side for regular accounts and ISA.
Notes and assumptions
About ISA Calculator
The ISA Calculator is a free, browser-based tool that estimates Korean ISA (Individual Savings Account) gains, tax treatment, and after-tax outcomes for stock, ETF, bond, RP, and deposit-interest scenarios. It runs entirely in your browser, so the numbers you enter never leave your device.
It has two modes. The trade mode compares a regular account against an ISA for a single buy and sell, showing the trade gain, the modeled exemption, and the tax saved at the ISA separate rate of 9.9% versus the standard 15.4%. The dividend mode lets you set daily, weekly, monthly, or yearly ETF purchases, a per-period dividend rate, and a monthly, quarterly, or yearly payout cadence, then charts the accumulating basis and the gross and after-tax dividend cash flow.
Use it to sanity-check whether an ISA is worth it for a given holding period, to see how much of a payout stays tax-exempt within the limit, or to plan recurring ETF contributions against the annual and total caps. You can also load researched ETF presets to fill the inputs quickly.
Results are estimates for reference, not professional financial or tax advice. Account types, exemptions, the 9.9% separate rate, and contribution limits follow the Restriction of Special Taxation Act information available on the reference date shown in the tool; Super ISA values and the yearly-basis exemption are modeled assumptions, not finalized law, and financial-income comprehensive taxation is not fully modeled.
Frequently asked questions
- What is the difference between the trade and dividend modes?
- Trade mode compares the tax on a single buy-and-sell in a regular account versus an ISA. Dividend mode models recurring ETF purchases and projects the period-by-period dividend cash flow, both before and after tax, with a chart.
- Does this give an official ISA tax amount?
- No. It produces estimates for reference based on the Restriction of Special Taxation Act as of the reference date shown in the tool. Super ISA limits and some restrictions are modeled assumptions, so confirm your actual situation with a financial institution or tax professional.
- Is my financial data sent anywhere?
- No. All calculations run locally in your browser using the values you type, and nothing is uploaded to a server.