Capital Gains Tax Calculator
Subtract expenses, the long-term holding deduction, and the basic deduction from a property gain, then apply progressive rates.
A simple estimate using general rates and deduction. Confirm actual tax with a professional or the tax service.
How the calculation works, stage by stage
The tool moves through a chain of steps, and each one feeds the next. First it finds your gross gain: sale price minus purchase price minus allowable expenses. If the property was held for three years or more, it then subtracts the general long-term holding deduction, which grows by 2% for every year held and caps at 30% (reached at 15 years) under the general property basis (table 1). That produces your taxable gain. From there it removes the 2.5 million won basic deduction to reach the tax base, applies the progressive brackets of 6% to 45%, and finally adds local income tax equal to 10% of the calculated national tax. Because the steps are sequential, a change early in the chain, such as a larger recognized expense or a longer holding period, ripples through every later step and can move the final number more than people expect.
A worked example with real numbers
Suppose you bought at 500 million won, sell at 900 million won, and have 30 million won of recognized expenses (acquisition tax, brokerage, and legal costs). Your gross gain is 900 minus 500 minus 30, which is 370 million won. If you held the home for 10 full years, the general long-term deduction is 10 times 2%, or 20%, which equals 74 million won. That leaves a taxable gain of 296 million won. Subtracting the 2.5 million won basic deduction gives a tax base of 293.5 million won. The tool then applies the 6% to 45% progressive brackets to that base and adds 10% local income tax on top of the national tax it computes. Notice that the 20% holding deduction alone stripped 74 million won out of the taxable amount before any rate was applied.
Why the holding period is your biggest lever
For most sellers the single largest variable they can still control is how long they hold. Under the general basis the deduction rises 2 points every year from year three onward, so the gap between selling at year 9 (18%) and year 15 (30%) can be large on a sizeable gain. On a 370 million won gain, moving from 18% to 30% changes the deducted amount from 66.6 million won to 111 million won, a 44.4 million won swing in the taxable base before progressive rates even enter the picture. This is exactly why it helps to run the numbers at several target years instead of one fixed date. A short delay is not always worth it, but only a side-by-side comparison shows whether waiting pushes you into a materially lower base.
When and how to use it
- Pre-sale simulation: enter a target sale price to estimate the tax burden and gauge your net proceeds before you list.
- Holding-period comparison: check the taxable base at 3, 5, 10, and 15 years to see how much the long-term deduction grows over time.
- Expense planning: input acquisition tax, brokerage, and legal fees to see how recognized costs lower the tax base, and keep the receipts that support them.
- Break-even thinking: compare a slightly higher sale price now against a longer hold with a bigger deduction, so you can weigh timing against price.
Common mistakes and misconceptions
- Mixing up the two deduction tables: this tool uses the general basis (table 1, up to 30%). A qualifying single high-value home can reach up to 80% under table 2, which this estimate does not model.
- Assuming the single-home exemption applies automatically. It has residence and holding conditions and is not built into this simple estimate.
- Treating routine repairs and maintenance as deductible. Generally only capital expenditures that add value (for example a balcony expansion) count, not everyday upkeep.
- Forgetting local income tax. The 10% local income tax is added on top of the national tax, so the headline bracket rate is not the whole cost.
- Overlooking short-term surcharges. Very short holds (under 1 to 2 years) can face higher rates that this general estimate does not reflect.
What this simple estimate leaves out
- It uses general progressive rates and the general long-term deduction only. It does not reflect single-home exemptions, multi-home surcharges, short-term surcharges, or regulated-area rules.
- Your actual result can vary greatly with sale timing, your number of homes, and exemption eligibility, so treat the output as a directional reference rather than a final figure.
- The 15-year, 30% cap and the 2.5 million won basic deduction reflect the general basis; a qualifying single home may follow a different, more generous path (table 2).
- Always confirm your specific case with a licensed tax accountant or the National Tax Service (Hometax) simulator before making a decision. This tool is for planning and comparison, not for filing.
The amounts you enter are calculated only in your browser and are never sent to or stored on a server. You can enter sensitive figures like transaction prices safely.
Read the Privacy Policy →Frequently asked questions
How is the long-term holding deduction applied here?
This calculator uses the general property basis, known as table 1: 2% for each year from year three, rising to a 30% cap at 15 years. A single high-value home may instead qualify for up to 80% under table 2, based on residence and holding requirements. Because this tool only models table 1, a qualifying single-home case can produce a very different real result.
Does it handle the single-home exemption?
No. This is a simplified estimate that ignores exemptions and reductions. The single-home exemption and temporary two-home rules have detailed residence and timing conditions, so you should confirm eligibility with a tax accountant or the official simulator rather than assuming it applies.
What counts as deductible expenses?
Recognized costs generally include acquisition tax, brokerage fees, legal costs, and capital expenditures that add value, such as a balcony expansion. Routine repairs and ordinary maintenance are usually not recognized. Keep the supporting receipts, and check the tax authority's criteria because what qualifies can be specific.
Why is my real tax bill different from this estimate?
The estimate uses general rates and the general long-term deduction, so it does not include single-home exemptions, multi-home or short-term surcharges, or regulated-area rules. Your actual liability also shifts with sale timing and how many homes you own. Use this number to compare scenarios, then verify the exact amount through Hometax or a tax professional.
Does holding longer always lower the tax?
A longer hold increases the general deduction by 2 points per year up to 30%, which reduces the taxable base and usually the tax. But the outcome also depends on your number of homes, any short-term surcharge for very brief holds, and exemption eligibility, so longer is typically but not automatically cheaper. Compare a few target years for your own situation before deciding.
Are the amounts I enter stored anywhere?
No. All calculation happens only in your browser, and the amounts you type are never sent to or saved on a server. You can refresh or close the page and nothing is retained.