Earn a few million won on the side in Korea and the same question follows: "do I have to file in May?" The internet answer is a slogan — "business income always, other income above 3 million" — so we opened the provision it rests on.
It is Income Tax Act art. 73 (exceptions to the final return). ⭐ And the provision does not define who must file. It lists, in nine subparagraphs, only those who need not. Fall outside the list and you file.
As of July 2026 — the opening line reads "a resident falling under any of the following subparagraphs may, notwithstanding arts. 70 and 71, choose not to file a final return on the tax base for such income." Filing is the default; art. 73 is the carve-out.
⭐⭐⭐ We ran the combinations through the provision
| Your income mix | Where it lands in art. 73 | May final return |
|---|---|---|
| Employment income only | (1)1 — "a person having only employment income" | exempt |
| Employment + separately taxed other income | (1)9 — a person under subpara. 1 who also has separately taxed income | exempt |
| Employment + business income (the 3.3%) | ⚠️ this combination appears in none of the nine | ⚠️ required |
| Employment income from two or more payers | ⚠️ (2) — "paragraph (1) shall not apply" | ⚠️ required |
| Other income above 3M won | loses separate taxation, so falls outside subpara. 9 | ⚠️ required |
⭐⭐ Paragraph (2) is the one people miss. "Paragraph (1) shall not apply to a person having any of the following income received from two or more persons (excluding daily workers)" — employment income included. A second job that pays wages triggers a filing duty too.
⭐ It carries a proviso, though: "provided that this shall not apply to a person who, through the year-end settlement … and payment of income tax …, has no tax payable on the final return." Settle both salaries at year-end with nothing left owing and the exemption survives.
⚠️⚠️ "Employment plus business income" is simply not in the list. Paragraph (1) enumerates combinations ending in "only" — only employment, only retirement, only public pension — and a few pairs of those. The moment 3.3%-withheld side income sits alongside a salary, you are outside it.
⭐ "Separate taxation" is what the exemption hangs on
Subparagraph 9 forgives separately taxed interest, dividend, pension and other income. What counts as separately taxed is set — in won — by art. 14(3).
| Income | Threshold | Provision |
|---|---|---|
| Other income | other income amount of 3M won or less, withheld | art. 14(3)8(a) |
| Interest and dividends | 20M won combined or less, withheld | art. 14(3)6 |
| Residential rental | gross receipts of 20M won or less | art. 14(3)7 |
⚠️⚠️ Only the other-income test uses a net figure. Interest, dividends and rent are measured on the combined amount or gross receipts — money received. Other income is measured after necessary expenses, so for personal services (60% deemed expense) 7.5 million won of fees equals 3 million won of other income (our arithmetic: 7.5M x 40% = 3M).
⭐ And subparagraph 8(a) ends with a proviso beginning "provided that, where a resident with such income …" — separate taxation is elective. Someone in a low bracket may prefer to combine.
The 3.3% is a separate matter from filing
Withholding applies a flat percentage to the gross payment. Art. 129(1)3 sets "3/100 on business income subject to withholding", and Local Tax Act art. 103-13(1) adds "10/100 of the income tax withheld", giving 3.3% (our arithmetic).
⭐ That percentage sees none of your expenses, dependants or salary. So filing produces refunds in some cases and extra tax in others. The full breakdown is in where the freelance 3.3% actually comes from.
⚠️ On not filing, the government guidance says: "you cannot receive various tax credits and reductions, and may bear heavy penalty taxes." ⚠️ The specific penalty rates are not on that page — it points to the National Tax Service.
When, where, and what gets combined
- Window — art. 70(1): "from 1 May to 31 May of the year following the taxable period, to the head of the competent tax office."
- Taxable period — art. 5: 1 January to 31 December.
- Place of tax payment — art. 6(1): "the place of tax payment for a resident's income tax shall be the place of domicile" (residence if none). Not the employer's address.
- What combines — art. 4(1): global income is interest, dividend, business, employment, pension and other income. Retirement income and capital gains are excluded.
- How — verbatim: "electronic filing via Hometax, electronic filing via mobile Sontax, or filing through a tax agent …"
Liability by bracket is in the comprehensive income tax article, your own figures in the calculator, and missed years in the amended return.
⚠️ What we removed from the earlier version
These sentences were in the previous edition and are not supported by anything we opened. Plausible-sounding claims are the dangerous kind, so they are listed rather than quietly dropped.
| Removed | Why |
|---|---|
| "The tax office automatically receives Naver, Coupang and Google settlement data" | ⚠️ no source found |
| "Paying health insurance separately hides side income from your employer" | ⚠️ no source found |
| "Non-filing penalty 20%, 40% if fraudulent" | ⚠️ in the Framework Act on National Taxes, which we did not open |
| "In 2026 the deadline moves to 1 June" | ⚠️ we could not confirm the extension rule. The provision says 31 May |
| "Reference rates of 6% and 15%" | the art. 55 table is published only as an image; linked to a separate article instead |
Questions that remain
My side income is small — does that exempt me?
⚠️ Art. 73 contains no monetary test. The exceptions are defined purely by the combination of income types. Business income in the mix puts you outside the list regardless of size.
Will my employer be told?
⚠️ We could not confirm this. What the provisions establish is that tax is filed at your place of domicile (art. 6(1)); we found nothing governing employer notification. The earlier version's "you are not automatically reported" had no source either, so we make no claim.
Is blog or video income business income?
The test is character, not amount: "income from activity carried on continuously and repeatedly on one's own account and responsibility for profit" (art. 19). ⚠️ Which side a particular case falls on depends on the substance, so we do not decide it here.
Do Korean stock gains combine?
Art. 4(1) excludes capital gains from global income. ⚠️ Which disposals are taxable at all is governed separately and is out of scope here. Interest and dividends above 20 million won combined do come into global taxation (art. 14(3)6).
What about severance pay?
No. Art. 4(1) separates retirement income from global income.
Sources
- ⭐⭐⭐ Korean Law Information Center — statute — Income Tax Act art. 73 (exceptions to the final return) (in force 1 Jan 2026, Act no. 21221). Source for the nine exemption subparagraphs, the "two or more payers" exclusion in paragraph (2), and its proviso.
- ⭐⭐⭐ Korean Law Information Center — statute — Income Tax Act art. 14 (computation of the tax base). Source for the 3M / 20M / 20M won thresholds and the proviso making separate taxation elective.
- ⭐⭐ Korean Law Information Center — statute — Income Tax Act art. 129 (withholding tax rates). Source for 3/100 on business income.
- ⭐⭐ Korean Law Information Center — statute — Local Tax Act art. 103-13 (duty of special collection). Source for "10/100 of the income tax withheld".
- ⭐⭐ Ministry of Government Legislation, Easy-to-Find Practical Laws — "Comprehensive real estate holding tax and comprehensive income tax" (page states as of 15 June 2026). Source for the six categories of global income (art. 4(1)), the taxable period (art. 5) and the place of tax payment (art. 6).
- ⭐ Ministry of Government Legislation, Easy-to-Find Practical Laws — "Delivery app workers > Filing the comprehensive income tax return" (page states as of 15 July 2026). Source for the definition of business income, the May window, the consequence of not filing and the filing methods.
- Our own arithmetic — 3% x 1.1 = 3.3%, 7.5M won of fees = 3M won of other income, and the required / exempt verdicts, which are our matching of each combination against the provision.
What we could not confirm
- ⚠️⚠️ Penalty rates. They sit in the Framework Act on National Taxes, which we did not open. The guidance says only "heavy penalty taxes."
- ⚠️⚠️ Employer notification and health insurance effects. Nothing in what we opened governs either, so both claims from the earlier version are gone.
- ⚠️ Deadline extension. The provision says 31 May. We did not check the rule for deadlines falling on a holiday.
- ⚠️ Art. 73(1)4's "business income prescribed by Presidential Decree." Determining its scope requires the Decree, which we did not open — so that case is absent from the table.
- ⚠️ The income tax rate table. Art. 55(1) is published as an image on the legal information service and could not be read as text.
- ⚠️ Classifying platform earnings. Whether activity is "continuous and repeated" turns on substance, so we decide no individual case.
Art. 73 does not list who must file — it lists who need not. If your combination is not on that list, the default applies.
As of July 2026 (Income Tax Act and Local Tax Act in force 1 Jan 2026; guidance pages as of 15 Jun and 15 Jul 2026). Provisions and amounts are the Korean Law Information Center and the legal guidance service verbatim; the per-combination verdicts and the multiplications are ours. ⚠️ This is not tax advice — how a particular income is classified depends on substance, so confirm through Hometax or a tax professional.
