Detached House Sale Capital Gains Tax Calculator

This calculator works out capital gains tax on the sale of a detached house together with its land. Unlike an apartment, a detached house is a building on a separate plot, and Korean tax law treats only a limited area of that plot as land belonging to the house. Anything beyond that line is treated as bare land, and it is taxed on entirely different terms. Enter the building's footprint, the total plot area, the zone the house is in, the sale and purchase prices split between building and land, and your holding and residence periods, and the calculator divides the plot into a house portion and an excess-land portion, taxes each separately, and adds them up.

The result shows the total tax, the area of garden that is taxed as land, and the difference between that tax and what you would have paid had the garden been within the limit. That last figure is the reason this page exists. A general capital gains calculator gets this wrong both ways: choose "house" and it treats the whole garden as house, badly understating the tax; choose "land" and it treats the house as land, throwing away the exemption altogether.

Anyone selling a detached house, a country house or a farmhouse on a large plot. The classic case is a single-home household that has owned a small building on several hundred pyeong of land for years, assumes the sale is tax-free, signs, and is then hit with a large bill on the excess land. Run the figures here before you sign to see whether any of the plot is over the limit.

It also matters for people clearing an inherited house in the countryside. Outside urban planning zones the multiplier is generous and most gardens fit inside it, but if the area has since been brought into an urban zone the multiplier drops and an excess can appear. It is also useful when negotiating with the buyer how to split the price between building and land in the contract, because that split changes the tax.

Step one is the area test. Under 소득세법 제89조제1항제3호, only land up to the building's footprint multiplied by a regional factor counts as part of the house. The factors are set by 시행령 제154조제7항: within urban planning zones, 3 times the footprint in residential, commercial and industrial areas of the capital region, 5 times in green-belt areas of the capital region, 5 times elsewhere in urban zones, and 10 times outside urban zones. The base is the footprint, meaning the area the building actually occupies on the ground as shown in the building register, not the total floor area.

Step two is apportioning the price. Only the land price is split. The building is wholly part of the house, so its price goes entirely to the house portion, and the land price is divided between the area inside the limit and the excess in proportion to area. Expenses are split in proportion to each portion's sale price. Step three applies the single-home exemption to the house portion. You need two years of ownership, plus 2 years of residence if the area was a regulated zone when you bought. If the combined sale price of the house and its qualifying land is at or below ₩1.2 billion the house portion is fully exempt; above that, only the proportion above the line is taxed. The excess land does not count towards that ₩1.2 billion test.

Step four is the long-term holding deduction under 제95조제2항. A single home lived in for at least 2 years gets Table 2 on the house portion, up to 40% each for ownership and residence and 80% in total, but the excess land is not a house and only ever gets Table 1, capped at 30%. Step five deducts the basic allowance of ₩2,500,000 once, under 제103조제1항, not once per portion. Finally the two portions' tax is added, then compared under 제104조제5항 with the tax on the combined base at the ordinary progressive rates, and the higher figure is used, with local income tax of 10% on top. If the excess land is classed as non-business land, its rate rises by 10 percentage points in every bracket.

Take a house in a residential area of an urban zone in the capital region, with a 100㎡ footprint on a 500㎡ plot. At 3 times the footprint, 300㎡ counts as house and 200㎡ is land. Of the ₩1.7 billion land price, 60% or ₩1.02 billion goes to the house portion and ₩680 million to the excess land. The ₩300 million building price goes wholly to the house, so the house portion sells for ₩1.32 billion against a purchase cost of ₩540 million. With 15 years of ownership and 10 of residence in a single home, the exemption applies, but ₩1.32 billion is above ₩1.2 billion, so only one eleventh of the ₩760.2 million gain, about ₩69.1 million, is taxable, and after the 80% Table 2 deduction the income is about ₩13.8 million.

The excess land sells for ₩680 million against ₩260 million, a gain of ₩409.8 million; after the 30% Table 1 deduction the income is ₩286.86 million. Deducting the single ₩2,500,000 allowance gives a combined base of about ₩298.2 million, tax of about ₩93.4 million, and with local income tax a total of ₩102,706,000. Had the plot been 300㎡ and inside the limit, the tax would have been ₩18,089,500, so the extra 200㎡ costs ₩84,616,500. If that 200㎡ were classed as non-business land, the total would rise to ₩129,120,320.

The most common one is assuming that a single-home household pays nothing. The exemption attaches only to the house and its qualifying land; garden beyond the limit was never part of the house. The next is using total floor area for the limit. A two-storey house has twice the floor area of its footprint, which inflates the limit. The multiplier applies to the ground the building stands on.

Splitting the price wrongly is another frequent error. Dividing the whole sale price by area splits the building price too, and the more valuable the building, the further off the result. The building goes entirely to the house portion; only the land price is divided. If the contract does not separate building and land, the split follows the ratio of official assessed values, and since that changes the tax, it is safer to agree the split at the contract stage.

Claiming the ₩2,500,000 basic allowance on each portion is also common. It is one sale by one person in one year, so it comes off once. Finally, people fail to check whether the excess land counts as non-business land. Garden used with the house is usually business-use, but the excess can be classed otherwise, and then the whole rate table becomes heavier. This calculator does not handle the temporary two-home, inherited-home or rural-home special cases, so if any of those apply, check separately.