Capital gains tax often lands as one large bill. Article 112 of Korea’s Income Tax Act lets a resident whose tax on a preliminary return (Art. 106) or a final return (Art. 111) each exceeds 10 million won pay part of it within two months after the payment deadline. How much may wait is set by Enforcement Decree Article 175: if the tax is 20 million won or less, the amount over 10 million won; if it exceeds 20 million won, up to 50% of the tax. Enter the tax and the due date to see what to pay now, what may wait, and the installment date.
1. The tax must exceed 10 million won — exactly 10 million won does not qualify (Art. 112).
2. Up to 20 million won: the part over 10 million; above 20 million: up to half (Decree Art. 175).
3. Preliminary and final returns are judged separately, and the deferred part is due within 2 months after the deadline.
Calculator
Updates as you type. Enter the tax for one return (the preliminary return and the final return are judged separately). The installment date is our sum: two months from the day after the due date. Weekend and holiday moves are not applied; local income tax is not included.
The installment rules
| Type | What the source says | Worth noting (ours) |
|---|---|---|
| Income Tax Act Art. 112 | A resident whose tax payable under Art. 106 or Art. 111 each exceeds 10 million won may pay part of it in installments within two months after the payment deadline, as the Decree provides. | “Each” — preliminary and final payments counted separately |
| Decree Art. 175(1) | If the tax payable is 20 million won or less: the amount exceeding 10 million won. | 15 million won → 5 million |
| Decree Art. 175(2) | If the tax payable exceeds 20 million won: 50/100 or less of the tax. | 30 million won → up to 15 million |
| Income Tax Act Art. 106 | On a preliminary return, pay the computed tax less reductions (preliminary payment). | The “tax payable” behind the test |
| Income Tax Act Art. 111 | By the final return deadline, pay the computed tax less reductions and credits (final payment). | Final return: 1–31 May of the next year (Art. 110) |
The words “a resident” mean installments are open to residents. The article says the taxpayer “may” pay in installments, so it is a choice. We did not read the application form or procedure.
How much may wait — our examples
| Tax payable (our example) | By the deadline / later | Worth noting (ours) |
|---|---|---|
| 9 million won | 9 million / 0 | 10 million or less — no installment |
| 10 million won | 10 million / 0 | Not “exceeding”, so no |
| 15 million won | 10 million / 5 million | Item 1: the part over 10 million |
| 20 million won | 10 million / 10 million | End of item 1, “20 million or less” |
| 30 million won | 15 million / 15 million | Item 2: up to half |
The two items join without a jump. At 20 million won, item 1 lets 10 million wait; just above 20 million, item 2 lets half wait, again just over 10 million (our sum). Item 2 says “50/100 or less”, so deferring less than half is fine too. The calculator shows the maximum and drops fractions of a won.
When is the installment due — our sums
| Due date (our example) | Installment due (our sum) | Worth noting (ours) |
|---|---|---|
| 30 Nov 2026 (preliminary return, September sale) | 31 Jan 2027 | Preliminary deadline: 2 months from the end of the month of sale (Art. 105(1)1) |
| 31 May 2027 (final return) | 31 Jul 2027 | Final return 1–31 May (Art. 110) |
| 31 Dec 2026 | 28 Feb 2027 | No 31 February, so month-end |
The article only says “within two months after the payment deadline”. We count two months from the day after the deadline and take the day before the matching date. The Framework Act on National Taxes moves deadlines that fall on Saturdays or holidays, but the calculator does not apply that. Weekend moves and the deadline by asset type are in capital gains tax preliminary return deadline calculator.
Global income tax has the same kind of installment (Income Tax Act Art. 77); see income tax installment calculator.
Checklist
- ☐ The tax on this return exceeds 10 million won
- ☐ Up to 20 million: the part over 10 million; above: up to half
- ☐ Preliminary and final payments counted separately
- ☐ Deferred part due within 2 months after the deadline
- ☐ Local income tax checked separately
Questions that remain
Two sales in a year add up to over 10 million won?
Article 112 asks whether the tax under Art. 106 or Art. 111 “each” exceeds 10 million won, so we read each return on its own (our reading).
Is there a penalty on the deferred part?
The two provisions we read say nothing about it. Penalties for missing the installment date sit in the Framework Act on National Taxes, which we did not read this time.
Can local income tax be split too?
Local income tax is under the Local Tax Act, which we did not read. Check Wetax or your local government.
Sources
- Korean law database (law.go.kr) — Income Tax Act Arts. 105, 106, 110–112 — source (current text, effective 1 July 2026, Act No. 21221; checked 2 November 2026). Art. 112 installments (each over 10 million won, within 2 months after the deadline), Art. 106 preliminary payment, Art. 111 final payment, Art. 105 preliminary deadline, Art. 110 final deadline.
- Korean law database — Income Tax Act Enforcement Decree Art. 175 — source (current text, effective 1 October 2026, Presidential Decree No. 36737; checked 2 November 2026). The installment amounts (over 10 million up to 20 million; half above 20 million).
- Not read. The application procedure and form, Framework Act penalties and deadline rules, the Local Tax Act.
- What we added. The “worth noting” column and the Korean everyday gloss.
Where to check further
- Hometax capital gains return — how to apply for installments.
- Wetax — local income tax.
Written on 2 November 2026. The content is from the source; the glosses are ours.
