Korea's 183 Days Can Now Span Two Tax Years. A Gap Resets Them.

Korean income tax turns on one number, and the number has not moved in a decade. An individual who keeps a place of residence in Korea for 183 days is a resident, taxed on worldwide income. An individual who does not is a non-resident, taxed only on Korean-source income. What changed is not the 183. What changed is the frame you are allowed to count it in, and the frame is the whole argument.

The Scene

A software contractor lands at Incheon on 1 October 2025 with a twelve-month client engagement and no family in Korea. She rents a serviced apartment, registers no domicile anywhere else in the country, and stays. Her accountant back home wants one date: the day Korea starts taxing the income she earns from her other clients abroad.

Read the headline rule and the answer looks obvious. One hundred eighty-three days after 1 October 2025 lands in early April 2026, so early April it is. Read the implementing decree and two other answers appear. One is 2 July 2026, three months later. One is no date at all, if she takes the wrong holiday in January. The gap between those answers is not a matter of interpretation style. It sits in the text of a single paragraph that was rewritten in 2025, and in a counting rule from the decree's opening lines that rarely gets quoted.

This is a footnote problem, which means it is a reading problem. The statute gives the threshold. The decree gives the clock. The clock has a start rule, a pause rule, and two different windows it is allowed to run in, and the four interact.

What the Rule Actually Says

The threshold lives in the Income Tax Act. In the version in force from 1 January 2026, Act No. 21221, the National Law Information Center's text of Income Tax Act Article 1-2 (Definitions) reads: "거주자"란 국내에 주소를 두거나 183일 이상의 거소(居所)를 둔 개인을 말한다 — a resident means an individual who has a domicile in Korea or has had a place of residence of 183 days or more. The next item is the mirror: "비거주자"란 거주자가 아닌 개인을 말한다 — a non-resident means an individual who is not a resident. The article carries amendment dates of 2010, 2014 and 2018, and the 2014 amendment is the one that replaced a one-year test with the 183-day test.

The Act stops at the threshold. The counting rule, and the definitions of the two routes it names, sit in the Enforcement Decree. The National Health Insurance Service statute service text of the Enforcement Decree of the Income Tax Act judges a domicile in Article 2 by 국내에서 생계를 같이 하는 가족 및 국내에 소재하는 자산의 유무등 생활관계의 객관적 사실에 따라 판정한다, the objective facts of living relationships such as family sharing a livelihood in Korea and assets located in Korea, and defines a place of residence as 주소지 외의 장소 중 상당기간에 걸쳐 거주하는 장소로서 주소와 같이 밀접한 일반적 생활관계가 형성되지 아니한 장소, a place other than one's domicile where a person lives for a considerable period without the close general living relationship a domicile has.

Then comes the clock, in "제4조", Article 4, titled 거주기간의 계산, calculation of the period of residence. Paragraph 1 moves every date in this article: 국내에 거소를 둔 기간은 입국하는 날의 다음날부터 출국하는 날까지로 한다 — the period of having a place of residence in Korea runs from the day after the day of entry to the day of departure. The arrival day is not counted. The departure day is.

Paragraph 2 is the pause rule, and it runs the other way. Where a person who had a place of residence in Korea leaves and re-enters, and the purpose of that departure — tourism or medical treatment are the decree's own examples — is recognised as plainly temporary in light of such facts as where the family sharing a livelihood lives and where the assets are, 그 출국한 기간도 국내에 거소를 둔 기간으로 본다 — that period abroad is also deemed a period of having a place of residence in Korea.

Paragraph 3 is where one number became two readings. In the version in force on 2 August 2022, Presidential Decree No. 32830, the National Law Information Center print of the Enforcement Decree of the Income Tax Act had one flat sentence: 국내에 거소를 둔 기간이 1과세기간 동안 183일 이상인 경우에는 국내에 183일 이상 거소를 둔 것으로 본다 — where the period of having a place of residence in Korea is 183 days or more during one taxable period, the person is deemed to have had a place of residence in Korea for 183 days or more. One window, one calendar year, because an individual's taxable period is the calendar year.

The current paragraph 3 is a list of two. The stem now reads 국내에 거소를 둔 기간이 다음 각 호의 어느 하나에 해당하는 경우에는 국내에 183일 이상 거소를 둔 것으로 본다, where the period falls under either of the following items, and the items are 1과세기간 동안 183일 이상인 경우, 183 days or more during one taxable period, and 2과세기간에 걸쳐 계속하여 183일 이상인 경우, 183 days or more continuously spanning two taxable periods. The amendment history on the paragraph adds a third date, 28 February 2025, to the 2015 and 2018 dates the 2022 print carries. On the National Law Information Center amendment history of the Enforcement Decree of the Income Tax Act, the decree promulgated on 28 February 2025 is Presidential Decree No. 35349, promulgated and effective the same day.

One word in the second item does the work: 계속하여, continuously. The second reading is not a two-year total. It is an unbroken run that happens to cross a year boundary.

The Numbers

Start with the case that fits inside a single taxable period. A person enters on 1 July 2026 and leaves on 31 December 2026. Article 4(1) drops the arrival day, so the count runs from 2 July to 31 December, which is 183 days. Item 1 of paragraph 3 is satisfied inside one taxable period and the person is a resident for 2026. Shift the arrival by one day, to 2 July, and the count runs from 3 July to 31 December: 182 days. Nothing else about the stay has changed, and the person is a non-resident for that year under the day-count route.

Now the contractor. She enters on 1 October 2025, so her count starts on 2 October. From 2 October to 31 December 2025 is 91 days, short of 183. Under the 2022 text, 91 days closed the 2025 question, and the 2026 count restarted from 1 January at zero.

Under the current item 2 the run does not restart. It continues across the boundary and reaches 183 days on 2 April 2026, because 1 January to 2 April 2026 is 92 days and 91 plus 92 is 183. That date is not decorative. Article 2-2 of the decree fixes the moment a non-resident becomes a resident, and one of its items is 국내에 거소를 둔 기간이 183일이 되는 날, the day on which the period of having a place of residence in Korea becomes 183 days. Her residency starts on the day the counter hits the number, not retroactively at entry and not at year end.

Compare the answer the old single-window text gives for the same unbroken stay. Counting only within 2026, from 1 January, the 183rd day is 2 July 2026. Two readings of one number, applied to one stay, give 2 April 2026 and 2 July 2026. The distance between them is 91 days, which is exactly the 91 she had already accumulated in 2025 and which the old frame discarded at midnight on 31 December.

The trap sits on the other side of the same word. Suppose a different person spends 100 counted days in Korea during 2025, goes home for six weeks for reasons that are neither tourism nor treatment, then spends 95 counted days in 2026. The two-year total is 195, comfortably past 183. Item 1 fails in both years, because 100 and 95 are each short. Item 2 asks for 183 days continuously spanning two taxable periods, and this run is not continuous. On the text, the day-count route leaves this person a non-resident, even though the arithmetic of 195 looks like it should not.

Paragraph 2 is the escape hatch, and it is narrower than it looks. If the six weeks abroad were recognised as plainly temporary, on the decree's own examples of tourism and medical treatment, the time abroad is deemed time with a place of residence in Korea. That repairs the continuity and the run becomes one stretch. A six-week assignment in another country for the same employer is a harder case, because the rule attaches to the purpose of the departure, not to its length.

One more number belongs here, because it is the same 183 doing a different job. Article 2 deems a person to have a domicile in Korea where they hold 계속하여 183일 이상 국내에 거주할 것을 통상 필요로 하는 직업, an occupation that ordinarily requires residing in Korea continuously for 183 days or more, or where they have family sharing a livelihood in Korea and, given their occupation and asset position, are recognised as likely to reside in Korea continuously for 183 days or more. That 183 is forward-looking. It is an expectation about a job, not a tally of days, and it does not pass through Article 4 at all. A person on a two-year employment contract can satisfy it on day one, while the day count still reads 1.

Where This Doesn't Apply

The day count is only one of the two routes into residency, and the other route can reach the answer first. Where Article 2 deems a domicile, Article 2-2 starts residency on the day that ground arose rather than on day 183. Anyone with a long employment contract and a family in Korea should test the domicile route before counting anything.

Article 3 of the decree removes another group from the arithmetic entirely: officers or employees dispatched to a resident's or domestic corporation's overseas business place, or to a foreign local corporation a domestic corporation wholly owns directly or indirectly, and public officials working abroad, 거주자로 본다, are deemed residents. Days outside Korea do not help them.

Paragraph 4 of Article 4 runs the opposite way for one group. Where an overseas Korean within the meaning of the Act on the Immigration and Legal Status of Overseas Koreans enters Korea and the entry is plainly temporary within the purposes set by ministerial rule, 해당 기간은 국내에 거소를 둔 기간으로 보지 아니한다, that period is not deemed a period of having a place of residence in Korea. For that group, days in Korea can be subtracted rather than added.

Nothing here resolves a tie between two countries. Where another state also treats the person as its resident, the applicable tax treaty decides, and the treaty tests are not day counts. The threshold also does not reach back indefinitely: for transfers made on or before 31 December 2014, the National Tax Service guidance on determination of non-residents and methods of taxation annotates the test as one year rather than 183 days, and the same parenthesis appears beside its description of the occupation-based domicile test.

Residency also decides scope, not rate. Becoming a resident on 2 April rather than 2 July changes which income Korea reaches and which filings follow, and those are separate questions from how much tax is due. Readers counting six months for a different Korean threshold should note that the health insurance clock is not this clock; The Seoul Footnote piece on counting six months for Korea's health insurance walks through a rule where days abroad move the start date instead of pausing it.

What Would Invalidate This

Three gaps in the primary record would change parts of this. First, the Addenda to Presidential Decree No. 35349 are not in hand. The promulgation and effective dates on the amendment history are both 28 February 2025, but an application provision in the Addenda could fix the first taxable period from which the continuous two-period item applies, and Korean practitioner commentary often describes the change as taking effect for 2026. That question is open here.

Second, the decree's amendment history lists six more amendments taking effect in 2026 alone, between 1 January and 1 July. Whether any of them touched Article 4 again was not confirmed article by article. The two-item structure quoted above was cross-checked against the Tax Tribunal's own text of the decree, but that page refuses automated retrieval, so it is corroboration rather than a quotable source. The statute service page used for the current wording also carries a superseded ministry name that the publisher's own print does not.

Third, the ministerial rule that fixes the qualifying purposes and the method of recognition in Article 4(4) was not retrieved, so the boundary between a temporary entry and an ordinary one is described here only as the decree describes it. The official English translation of the decree published by the Korea Legislation Research Institute is stamped Presidential Decree No. 33621 of 2023, before the 2025 amendment, and its Article 4 wording was not retrieved here. Every date in the worked examples was counted directly from Article 4(1) rather than taken from a published tax authority example.

If You Are Actually in This Situation

Write down two dates before anything else: the day after your entry, and the day of your departure if you have one. Those are the endpoints Article 4(1) gives you, and most of the confusion in this area comes from counting the arrival day. Then count forward to 183 and mark that calendar date, because under Article 2-2 it is the day residency begins if it begins by day count at all.

If the count crosses 31 December, do not discard the earlier year. Check whether the run is unbroken, and treat every trip out of Korea as a potential break rather than a neutral pause. Keep boarding passes and entry stamps for each trip, with a one-line note of its purpose, because paragraph 2 turns on purpose and the evidence for purpose is contemporaneous, not reconstructed.

Then test the other route. If your contract ordinarily requires staying in Korea for 183 days or more, or your family shares a livelihood here, Article 2 may make you a resident long before the counter reaches 183, and the day count will be the wrong argument. The same goes in reverse for anyone dispatched abroad by a Korean employer, who is a deemed resident under Article 3 regardless of days.

Finally, confirm the version. Pull the current Enforcement Decree text, read Article 4 paragraph by paragraph, and look at the amendment dates printed beside paragraph 3 before relying on any summary, English or Korean, that predates 2025. A 2022 print says one taxable period and stops; the current paragraph says two things. Readers sorting out which Korean obligations follow from a given status may find The Seoul Footnote piece on which self-employed foreign residents are covered and The Seoul Footnote piece on what happens when a foreign worker leaves Korea useful next, since both start from the resident or non-resident fork that this one number decides.