Once you have sold a home and received the final balance, the next few weeks usually disappear into moving, closing out loans and settling into a new place. By the time you stop and ask "when do I actually have to pay the capital gains tax?", a month or more may already have gone by. In Korea, capital gains tax on property is not withheld by anyone and the tax office does not send you a bill first. The seller has to work out the deadline, file the return and pay the tax on their own.
The catch is that the window is short. For real estate, the preliminary return is due within two months from the last day of the month in which the balance was paid, and the local income tax has to be filed separately within the same window. This guide walks through a deadline table based on real calendar dates, the cases where the deadline changes, the Hometax filing steps where people typically get stuck, and exactly how much extra you pay if you miss the date.
1. The deadline: two months from the end of the month you received the balance
If you sold land, a building, a home, or a right to real estate such as a pre-sale right or a redevelopment occupancy right, you must file a preliminary return and pay the tax within two months from the last day of the month that contains the transfer date. The transfer date is not the contract date. In principle it is the day the balance was paid. If the ownership transfer was registered before the balance was paid, the registration date counts instead, and the registration date is also used when the balance date is unclear.
The key point is that the clock starts at the end of the month, not on the day you were paid. Whether the balance came in on March 2 or March 30, the deadline is the same. If the last day falls on a Saturday, Sunday or public holiday, it moves to the next business day. The table below applies that rule to the actual 2026–2027 calendar.
| Balance paid (transfer date) | Start point (month end) | Preliminary return and payment due | Note |
|---|---|---|---|
| Jan 15, 2026 | Jan 31, 2026 | Mar 31, 2026 (Tue) | No shift |
| Mar 20, 2026 | Mar 31, 2026 | Jun 1, 2026 (Mon) | May 31 is a Sunday |
| Jun 10, 2026 | Jun 30, 2026 | Aug 31, 2026 (Mon) | No shift |
| Aug 25, 2026 | Aug 31, 2026 | Nov 2, 2026 (Mon) | Oct 31 is a Saturday |
| Oct 12, 2026 | Oct 31, 2026 | Dec 31, 2026 (Thu) | No shift |
| Nov 5, 2026 | Nov 30, 2026 | Feb 1, 2027 (Mon) | Jan 31 is a Sunday |
| Dec 18, 2026 | Dec 31, 2026 | Mar 2, 2027 (Tue) | Feb 28 is a Sunday and Mar 1 a holiday |
Weekends and holidays push the deadline out by a day or two, but relying on a rough "about two months" in your head is also how people end up a day late. To see the exact due date, its weekday and the number of days left from today in one place, plug the balance date into the date calculator.
2. What you sold changes the deadline
The two-month rule is the real estate rule. The same capital gains tax uses different reference points depending on the type of asset and the way it was transferred, so check which row your sale falls into first.
| Type of transfer | Preliminary return due | Final return |
|---|---|---|
| Land, buildings, homes, pre-sale and occupancy rights | 2 months from the end of the transfer month | May 1–31 of the next year (only if required) |
| Burdened gift (the debt portion taken over) | 3 months from the end of the transfer month | May of the next year (only if required) |
| Land-transaction permit zone, balance paid before permit | 2 months from the end of the permit month | May of the next year (only if required) |
| Taxable domestic shares (major shareholders, unlisted) | 2 months from the end of the half-year of transfer | May of the next year (only if required) |
| Overseas shares | No preliminary return | May 1–31 of the next year (mandatory) |
A burdened gift is when a parent hands a home to a child together with a mortgage or tenant deposit that the child takes over. The portion covered by that debt is treated as a sale, so the parent owes capital gains tax on it, and the deadline is three months to line up with the gift tax deadline. Because the child's gift tax return has to be handled at the same time, it helps to read our gift tax filing deadline and penalty guide so both schedules match.
Listed domestic shares are generally not subject to capital gains tax unless you are a major shareholder or traded off-exchange. If you are, the deadline is counted by half-year: shares sold between January and June are due by August 31, and shares sold between July and December are due by the last day of February the following year.
3. Filing the preliminary return in five steps
Step 1: Confirm whether you need to file at all
Not every sale requires a return. If a single-home household held the home for at least two years (and also lived in it for two years if it was in an adjustment zone when acquired) and sold it for 1.2 billion won or less, the gain is fully exempt and there is no filing obligation. If the sale price is above 1.2 billion won, the excess portion is taxable even for an exempt home, so you must file.
The trap is the sale you thought was exempt but was not. Missing the deadline for a temporary two-home exemption, a household separation that does not meet the rules, or a miscounted holding period can all break the exemption and leave you in "no return filed" status. If the exemption is at all uncertain, filing a return even with zero tax due is the safer route. If you want to review the tax rates and exemption rules themselves first, see our real estate capital gains tax calculator and rate guide.
Step 2: Gather your documents
Collecting evidence usually takes longer than filling in the form. Deductible expenses in particular are only allowed if you can prove them, and every missing receipt goes straight into higher tax.
- The sale contract and the original purchase contract (or the prior tax return and valuation records if you inherited or received the property as a gift)
- The certified property register
- Acquisition tax receipts, brokerage fee receipts for both purchase and sale, and legal scrivener fee receipts
- Tax invoices, card slips, cash receipts or bank transfer records for capital improvements such as new window frames, balcony extensions or boiler replacement
- Resident registration and family relation certificates if you are claiming a single-home exemption or another relief
Routine repairs such as wallpaper, flooring or a new sink are treated as maintenance rather than improvements, so they do not count as deductible expenses. If you need to dig up paperwork from a purchase ten years ago, start right after the balance is paid.
Step 3: Complete the return on Hometax
After logging in to Hometax, go to the tax filing menu, choose capital gains tax, then the preliminary return. A single, straightforward property sale can usually go through the simplified screen, while the standard screen is more accurate when long-term holding deductions or several reliefs are involved. The input order is roughly seller and buyer details, the asset (address, area, acquisition date, transfer date), acquisition and sale prices, expenses, and the holding and residence periods.
The most common mistake here is entering the contract dates. Both the acquisition date and the transfer date must be the balance date (or registration date) for the holding period and the long-term holding deduction to be calculated correctly. Falling one day short of two years switches you onto a completely different rate table, so enter the dates straight from your documents.
Step 4: Filing and paying are separate
Submitting the return produces a receipt, and many people close the window at that point. Filing and paying are separate steps, and if you do not actually pay, late-payment penalties start even though the return was filed. Pay on the payment screen that follows submission by bank transfer or card, or use the electronic payment number in your banking app. There is no longer a credit for filing the preliminary return on time (it was abolished in 2011), so you simply need to pay by the deadline.
Step 5: Continue on to local income tax
After the national return is done, the local income tax return is still outstanding. The next section covers it separately.
4. Local income tax must be filed separately
Capital gains tax brings with it a personal local income tax equal to 10% of the national tax. If your capital gains tax is 15 million won, the local income tax is 1.5 million won. Since 2020, local income tax has been separated from national tax and is filed and paid to the local government, with the same deadline as the capital gains tax preliminary return.
In practice, after you submit the capital gains return on Hometax a link screen to Wetax appears, pulls in the figures from your national return, and you only need to review and submit. The problem arises when people skip that screen and close the browser. The national tax is then filed but the local tax is not, and a separate penalty can be charged on the local income tax. If you missed the link, log in to Wetax directly and file there, then pay through Wetax or the local tax menu in your banking app.
Whether local income tax can be paid in instalments, and on what terms, is governed by local tax rules. Do not assume it mirrors the national instalment rules; confirm on the Wetax filing screen or with the tax department of your city, county or district office.
5. When you need a final return as well
Besides the preliminary return, capital gains tax has a final return filed from May 1 to May 31 of the following year. If you sold only one property in the year and filed the preliminary return correctly, you do not need to file a final return. The main cases where you do are:
- You sold two or more assets subject to progressive rates in the same year, and the tax changes once they are combined because they were not aggregated in the preliminary returns
- You sold overseas shares (there is no preliminary return, so the final return is the only filing)
- You did not file a preliminary return (filing late by the final return deadline reduces the penalty)
The first case is the one most people miss. If you sold land in the first half and a home in the second half and filed a separate preliminary return for each, each sale may have landed in a low bracket on its own, but combined the tax base is larger and a higher bracket can apply. The difference has to be settled in the May final return, and leaving it out triggers an under-reporting penalty.
6. What filing late really costs: penalty rules and worked numbers
Missing the deadline brings two kinds of penalty: a failure-to-file penalty for not filing, and a late-payment penalty for paying late.
| Item | Basis | Note |
|---|---|---|
| General failure-to-file penalty | 20% of tax due | No return filed at all |
| Fraudulent failure-to-file penalty | 40% of tax due | Fraud such as a double contract |
| Under-reporting penalty | 10% of the under-reported tax | 40% if fraudulent |
| Late-payment penalty | Unpaid tax × days late × 0.022% | Keeps accruing every day |
| Reduction for late filing | 50% within 1 month, 30% within 3, 20% within 6 | Applies only to the failure-to-file penalty |
| Missed preliminary return, filed by final deadline | 50% reduction of the failure-to-file penalty | If filed by the May final return deadline |
The difference is clearest in numbers. The table compares filing points for a computed tax of 15 million won (the 1.5 million won local income tax and its own penalties are extra).
| When the return is filed | Failure-to-file penalty | Late-payment penalty | Total paid | Versus on time |
|---|---|---|---|---|
| On time | 0 won | 0 won | 15.0 million won | Baseline |
| Late return 20 days after the deadline | 1.5 million won (10%) | about 66,000 won | about 16.56 million won | +1.56 million won |
| Late return 120 days after the deadline | 2.4 million won (16%) | about 396,000 won | about 17.79 million won | +2.79 million won |
| Filed with the May final return (about 364 days) | 1.5 million won (10%) | about 1.2 million won | about 17.70 million won | +2.70 million won |
| Never filed, assessed after 18 months (548 days) | 3.0 million won (20%) | about 1.81 million won | about 19.81 million won | +4.81 million won |
The same 15 million won tax bill can grow by more than 4.8 million won depending solely on when you file. Note how the failure-to-file penalty rises in steps according to the reduction bands, while the late-payment penalty keeps building every single day. If you have already missed the deadline, filing a late return and paying on the day you notice is almost always cheaper than waiting for the May final return.
7. If you cannot pay in one go, apply for instalments
Even after a sale, the cash often goes straight into the balance on a new home or into paying off a loan, leaving little to cover the tax. In that case you can use instalment payment.
- Eligibility: capital gains tax due of more than 10 million won
- Amount you can defer: if the tax is 20 million won or less, the portion above 10 million won; if it is more than 20 million won, up to 50% of the tax
- Instalment deadline: within two months after the original payment deadline
- How to apply: enter the deferred amount on the preliminary return when you file (no interest or collateral)
For example, with 15 million won of tax you pay 10 million won by the deadline and the remaining 5 million won two months later. With 30 million won of tax you can defer up to 15 million won. Instalments only split the payment; they do not postpone the filing, so the return must still be submitted by the original deadline.
8. Frequently asked questions (FAQ)
Q1. Is the deadline counted from the contract date or the balance date?
The balance date. The transfer date is in principle the day the full price was received, and if the registration was transferred before the balance was paid, the registration date applies. Counting from the contract date can make you set the deadline too early or miscount the holding period and land in the wrong rate bracket, so always work from the balance date.
Q2. Do I still have to file if my single home is exempt?
If the sale price is 1.2 billion won or less and the gain is fully exempt, there is no filing obligation. However, if the exemption turns out to be wrong you also carry the failure-to-file penalty, so it is safer to file when things are less clear-cut, for example when a temporary second home or an inherited home is involved. For a high-value home sold above 1.2 billion won, you must file a preliminary return for the excess portion.
Q3. I filed but entered the wrong amount. What now?
If you under-reported the tax, file an amended return. Amending within one month after the statutory deadline cuts the under-reporting penalty by 90%, within three months by 75%, and within six months by 50%. If you overpaid, you can claim a refund through a request for correction within five years. Finding an expense receipt after filing is the classic reason for such a claim.
Q4. Should I use a tax accountant or file myself?
Plenty of people file directly on Hometax when they have sold one property and have the purchase contract, the sale contract and all expense receipts. When the property was inherited and the acquisition price needs a valuation, or when a burdened gift, a mixed-use building or several reliefs overlap, one calculation error can mean millions of won, and professional review is usually worth the fee.
9. Check your tax and your deadline before you file
Before you file, you really need two numbers: roughly how much tax you owe, and the date you must pay it by.
Enter your acquisition price, sale price, expenses and holding period in the capital gains tax calculator and it returns an estimate with the long-term holding deduction and rate brackets already applied. That one figure answers several questions at once. If it is above 10 million won you can decide whether to request instalments, adding 10% shows your total burden including local income tax, and layering on 20% plus the days late, as in section 6, shows what missing the deadline would cost. Having the estimate before you start on Hometax also gives you a benchmark to check that the return's result looks right.
Use the date calculator with your balance date to see which day falls two months after the month end, what weekday it is, and how many days you have left. If you want to go over the rate tables and exemption rules first, read our real estate capital gains tax calculator and rate guide as well.
This article summarises general Korean tax rules as of 2026 for reference only. If you have inherited or gifted assets, reliefs to apply, or several sales to combine, confirm the final position with Hometax guidance, a tax professional or your local tax office.
