A foreign resident whose total period of domicile or residence in Korea in the ten years before the end of the tax year is five years or less is taxed on foreign-source income only to the extent it is paid in Korea or remitted to Korea (Income Tax Act, Art. 3(1), proviso). From the tax year in which the total exceeds five years, all income is taxable under the general rule.
Settle residency first — the proviso only matters for residents
The overseas income relief is a proviso that applies only to residents, so the starting point is residency. Article 1-2(1) of the Income Tax Act defines a resident as an individual with a domicile in Korea or a place of residence there for 183 days or more, and a non-resident as anyone who is not a resident. The two tests are joined by “or”, so a person can be resident without reaching 183 days if their domicile is in Korea. Under Article 1-2(2) the criteria for domicile, residence and resident status are set by Presidential Decree, so counting days is not the end of it: whether the family has moved too, whether the person works for a Korean employer on a continuing basis and where the main assets sit all come into play. A non-resident is taxed only on domestic-source income under Article 119 (Art. 3(2)), so the overseas income proviso never arises. A resident, by contrast, is taxed on all income under the main text of Article 3(1), and the question then becomes whether the proviso applies as an exception.
Five years means a total within ten, not a continuous stretch
The proviso to Article 3(1) taxes a foreign resident whose total period of domicile or residence in Korea in the ten years before the end of the tax year is five years or less only on foreign-source income paid in Korea or remitted to Korea. The word that is easily missed is “total”. It is not the length of the current stay but the sum of all periods of domicile or residence in Korea within the ten years counted back from the end of the tax year being assessed. Someone who worked in Korea for a few years, went home and has now returned will find the earlier stay counted if it falls inside the ten-year window. Relying on “I have only been back for two years” can lead to the wrong answer. Compile entry and exit records and past residence history first, and check individually any point where the count could be disputed. The proviso also applies only to foreign nationals, so nationality needs confirming as well.
The switch to worldwide taxation is tested again every tax year
The reference date is “the end of the tax year”. Each year the ten-year look-back is recalculated from that year’s end, so having qualified once does not carry over to the next year. In a tax year in which the total exceeds five years the proviso does not apply, and the main text of Article 3(1) brings in foreign interest and dividends, rent from property abroad and other income arising outside Korea regardless of whether anything was remitted. Anyone expecting a long stay should work out in advance from which tax year the total will pass five years and review their foreign assets and income around that point. Conversely, a person who leaves for a while and comes back may find the window has moved and the total has dropped to five years or less again. Either way, the answer depends on the year-by-year residence history and needs case-by-case review.
While the proviso applies, remittance records are what matter
Even under the proviso, foreign income does not drop out of tax altogether: foreign-source income paid in Korea or remitted to Korea is taxable. The recurring problem in practice is being unable to explain what money moved from an overseas account to a Korean one actually was. Whether it was that year’s foreign income, such as interest on overseas deposits or rent from property abroad, or savings and sale proceeds held before arrival and moved for living costs, can change the analysis, and which transfers count as remittances of foreign income can be contested on the facts. So it is worth recording the source account, the origin of the funds and the purpose each time money is sent, and considering keeping the account that receives income separate from the one holding existing funds. Recording where and how each item of foreign income is paid also helps when deciding whether it was paid in Korea.
Final return, foreign tax credit and the account-reporting exemption
Foreign income that becomes taxable is included in global income alongside Korean income. Article 70(1) requires a resident with global income for the tax year to file a return of global income between 1 and 31 May of the following year. If foreign tax has already been paid on remitted foreign income, a foreign tax credit within the limit under Article 57(1) can be considered. Overseas financial account reporting also needs attention. Article 54 of the Act on Adjustment of International Taxes exempts foreign residents covered by the proviso to Article 3(1) of the Income Tax Act from the reporting obligation. In a tax year in which the overseas income proviso applies, account reporting is therefore also exempt — but once the total passes five years and the proviso falls away, the exemption may go with it. In the year the scope of tax changes, check whether account reporting now applies as well.