Missed the deadline for a Korean income or capital gains tax return? Filing late is still better than not filing. The Framework Act on National Taxes provides a late return filed on your own initiative, and cuts the penalty for not filing the sooner you do it: 50% within a month, 30% within three, 20% within six. We read articles 45-3, 47-2, 47-4 and 48 as written.
1. The non-filing penalty is 20% of the tax due. It is 40% (60% for offshore transactions) where the failure involved fraudulent acts (art. 47-2(1)).
2. A prompt late return cuts that penalty. After the statutory deadline: within 1 month 50%, 1–3 months 30%, 3–6 months 20% off. Not if you filed knowing the tax office was about to determine the tax (art. 48(2)2).
3. The late-payment penalty is separate and grows daily. It runs at 22/100,000 a day and is not reduced — the later you pay, the more it grows (art. 47-4, Decree art. 27-4).
What a late return is — art. 45-3
Paragraph 1 A person who did not file a tax base return by the statutory deadline may file a late return before the head of the tax office determines and notifies the tax base and amount …
Paragraph 2 … a person with tax payable shall pay it.
Paragraph 3 … the head of the tax office shall determine or correct the tax base and amount and notify the filer within 3 months of the filing.
The window is “before the tax office determines and notifies.” After that, a late return is no longer possible.
Penalty relief — art. 48(2)2
| Time after the statutory deadline | Reduction in non-filing penalty | Basis |
|---|---|---|
| Within 1 month | 50% | Item (a) |
| Over 1 to 3 months | 30% | Item (b) |
| Over 3 to 6 months | 20% | Item (c) |
| Over 6 months | None | — |
The relief applies only to the article 47-2 non-filing penalty, and not where the return was filed “knowing in advance that the tax base and amount would be determined.” If you filed on time but under-reported, that is an amended return, with its own relief of 90% within a month down to 10% at two years (para. 2 item 1).
How much it matters — an example of 1 million won due
| Late return and payment | Non-filing penalty (from 200,000 won) | Late-payment penalty |
|---|---|---|
| 30 days late | 50% off → 100,000 won | 6,600 won |
| 90 days late | 30% off → 140,000 won | 19,800 won |
| 180 days late | 20% off → 160,000 won | 39,600 won |
| Never filing | 200,000 won | Keeps running until the notice |
Our example, assuming ordinary non-filing (20%) and a late-payment penalty of “1 million won × days × 22/100,000.” The 30, 90 and 180 days assume filing and payment on the same day; the relief bands are set in months (1, 3, 6), so the exact cut-offs depend on the deadline date.
Late-payment penalty — art. 47-4
Unpaid tax is multiplied by the days from the day after the statutory payment deadline to the day before payment (if paid before a notice) and by the Decree rate of 22/100,000 a day — about 8.03% a year (our arithmetic). This penalty is not covered by article 48(2)2, so pay together with the late return to stop it growing.
Checklist
- ☐ The statutory deadline — when do the 1-, 3- and 6-month marks fall?
- ☐ Has the tax office already determined and notified? If so, no late return
- ☐ File and pay together — the late-payment penalty runs daily
- ☐ Filed on time but wrongly? Use an amended return (relief from 90%)
Questions that remain
If no tax is due, is there no penalty?
The non-filing penalty is a percentage of “the tax payable on that return,” so with nothing payable it produces no amount. But for businesses required to keep double-entry books, article 47-2(2) charges the greater of that amount and 7/10,000 of revenue (14/10,000 for fraud), so a penalty can arise even with no tax due. The example above leaves that case out.
Does the relief apply if I file after the tax office contacts me?
Article 48(2)2 excludes returns filed “knowing in advance” that the tax would be determined, so relief reads as unlikely. Check with the tax office for your case.
Sources
- Framework Act on National Taxes [in force 11 Aug 2026] [Act No. 21860] — original text (checked 1 October 2026). Article 45-3 (late returns, before notice, determination within 3 months), article 47-2(1) (20%, 40%, 60%), article 47-4 (late-payment penalty) and article 48(2) (amended returns 90% to 10%; late returns 50%, 30%, 20%).
- Enforcement Decree of the Act, article 27-4 — 22/100,000 a day for late payment (the figure confirmed on 22 September 2026 for our side-job income tax article).
- Our own working. The penalties in the 1 million won example and 8.03% a year are our arithmetic.
Where to check further
- Tax dates — Korean tax calendar.
- Amended returns and refund claims — amended returns.
Written on 1 October 2026. Articles are from the National Law Information Center; the tables and examples are ours.
