Miss a Korean filing deadline or under-report and penalty taxes follow. Article 47-2 of the Framework Act on National Taxes adds 20% of the tax due for not filing by the deadline (interim returns included), 40% for fraud; Article 47-3 adds 10% of the under-reported part. On top comes a late-payment penalty per day late, at 22/100,000 a day under Decree Article 27-4. Unpaid tax of 10 million won, not filed and 100 days late, means 2.22 million won in penalties.
1. Non-filing 20% (fraud 40%), under-reporting 10% — interim returns included.
2. Late payment: 0.022% a day (22/100,000) × days late.
3. 10m, not filed, 100 days = 2m + 0.22m = 2.22 million won (our example).
Calculator
Updates as you type. Filing penalty on the tax due (or the under-reported part) plus 0.022% a day until payment or the payment notice. Offshore fraud (60%), the bookkeeping-revenue alternatives, the monthly 0.67% after a designated deadline and reductions for late filing are not included.
Filing penalties — Arts. 47-2, 47-3
| Type | What the source says | Worth noting (ours) |
|---|---|---|
| Non-filing (47-2(1)2) | No return by the deadline (interim and mid-term included): 20/100 of the tax due | Penalties and interest excluded from the base |
| Fraudulent non-filing (1)1 | 40/100; 60/100 for offshore fraud | — |
| Bookkeepers etc. (2) | Compared with a share of revenue (e.g. 14/10,000), the larger | Outside the calculator |
| Under-reporting (47-3(1)2) | 10/100 of the under-reported tax | — |
| Fraudulent under-reporting (1)1 | 40/100 (offshore 60) of the fraud part + 10/100 of the rest | — |
Late-payment penalty — Art. 47-4, Decree Art. 27-4
Unpaid or under-paid tax (including interim payments) × the days from the day after the due date to the day before payment (or the payment notice) × 22/100,000 a day. The Decree amended on 27 February 2026 also sets 67/10,000 a month for months elapsed after a designated payment deadline (Act Art. 47-4(1)1-2). The calculator covers only the daily part.
Three sums — our example
| Case (our example) | Penalties | Worth noting (our sum) |
|---|---|---|
| Tax 10m, not filed, 100 days late | 2.22 million won | 2m + 10m × 100 × 0.00022 = 0.22m |
| 4m of 10m under-reported, 30 days late | 466,000 won | 400,000 + 10m × 30 × 0.00022 = 66,000 |
| Tax 10m, fraud, 365 days late | 4.803 million won | 4m + 803,000 |
The second example applies late payment to the whole 10m; in practice it’s only the unpaid amount, so enter that as “tax unpaid” (ours). Reductions for late filing (Art. 48) are in late filing penalty relief; capital gains deadlines in interim return deadline calculator.
Checklist
- ☐ Interim returns count for non-filing
- ☐ 20% / 10% / 40%
- ☐ Late payment adds 0.022% a day
- ☐ File and pay as soon as you can
- ☐ Check late-filing reductions
Questions that remain
What is 0.022% a day over a year?
8.03% over 365 days (our sum: 0.00022 × 365).
Local income tax penalties too?
See local tax penalties; not included here.
Sources
- Korean law database (law.go.kr) — Framework Act on National Taxes Arts. 47-2 to 47-4 — source (current text, effective 2 October 2026, Act No. 21987; checked 20 October 2026). Non-filing 20%, fraud 40% (offshore 60%), interim returns included, bookkeeper rule, under-reporting 10%, late-payment formula, monthly method after a designated deadline (item 1-2).
- Korean law database — Enforcement Decree Art. 27-4 — source (effective 1 July 2026, Decree No. 36125; checked 20 October 2026). 22/100,000 a day, 67/10,000 a month (added 27 Feb 2026).
- Not read. Late-filing reductions (Art. 48); local taxes.
- What we added. The “worth noting” column and the Korean everyday gloss.
Where to check further
- NTS Hometax — late filing and penalties.
Written on 20 October 2026. The content is from the source; the glosses are ours.
