For people relocating from South Korea to the United States

Moving to the US From South Korea: Your First US Tax Year

Relocating from South Korea? The US decides tax residence by its own tests, your first year is usually split in two, and the US-South Korea treaty settles dual residence. Here is how each piece works.

Substantial presenceGreen card testDual-status yearTie-breakerSocial security

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Quick answer

When does someone moving from South Korea start paying US tax on worldwide income?

From the residency starting date: the first day in the US in a year you meet the substantial presence test, or the first day as a permanent resident under the green card test (IRS Pub 519). Before that you are a nonresident, so the first year is usually dual-status. If you are also resident in South Korea, Article 3 (Fiscal Domicile) of the treaty decides which country you are resident in for treaty purposes.

Prepared by Illuminous Accounting · Sources checked November 11, 2026

At a glance

When you become US resident: Green card test or substantial presence test (Code section 7701(b))
First year: Usually dual-status: nonresident, then resident
Treaty tie-breaker: Article 3 (Fiscal Domicile)
Social security agreement: Yes, since April 1, 2001
Accounts in South Korea: FBAR, Form 8938 and PFIC rules can apply once resident

The two US residency tests

Test	You are a US tax resident if	Source
Green card	You hold lawful permanent resident status at any time during the calendar year	Pub 519
Substantial presence	31 days this year and 183 weighted days over 3 years (all of this year, one third of last year, one sixth of the year before)	Pub 519

These come from Code section 7701(b). A work visa, a student visa or a move for family from South Korea all go through the same two tests; some visa holders can exclude days. Try the calculator.

The residency starting date

Expect your first year to have two halves. Income from South Korea before you became resident is generally outside US tax unless it is US-source; income after the residency starting date is taxed worldwide (IRS Pub 519). The starting date is your first day in the US in that year under the substantial presence test, or your first day as a permanent resident under the green card test. People who arrive near year end may be able to opt in early under the first-year choice. Getting the date right decides which Korean salary, bonuses and investment income the IRS sees.

Dual residence with South Korea

The US tests in Pub 519 do not override a treaty's own residence rules (IRS Pub 519). For people moving from South Korea: Article 3 (Fiscal Domicile) of the treaty has the tie-breaker for someone resident in both countries: it looks first at where you have a permanent home available, then at the further tests the article lists, in the order it sets them. A US return that relies on the tie-breaker needs Form 8833 (IRS), and long-term green card holders should check the section 877A consequences first.

Your accounts back home

Once you are a US resident, bank, pension and investment accounts you keep in South Korea can bring the FBAR and Form 8938, and funds held there are often treated as PFICs (Form 8621, IRS). See FBAR and FATCA and Form 8938 for who files and the thresholds.

Sources for moving from South Korea

Treaty

The IRS lists the 1976 income tax treaty, signed June 4, 1976. General effective date (IRS Table 3): treaty Jan. 1, 1980 (IRS treaty documents for Korea; treaty text; IRS Table 3).
Residence and tie-breaker: Article 3 (Fiscal Domicile).
Saving clause: paragraph 4 of Article 4 (General Rules of Taxation).
Article 23 (Private Pensions and Annuities) and Article 24 (Social Security Payments) and Article 25 (Exemption from Social Security Taxes), pensions.
Article 5 (Relief from Double Taxation), relief from double taxation.
Article 19 (Dependent Personal Services), employment income.

US law

US residency tests and starting dates: Code section 7701(b) (IRS Pub 519).
Treaty residence for dual residents: Treas. Reg. section 301.7701(b)-7, Form 8833 and section 6114; long-term residents: section 877A (IRS Form 8833).
Social security agreements: SSA list.

The rules of South Korea on leaving the country also apply; check them with a local adviser.

How we help

We start with your travel dates and your last Korean tax year, work out the residency starting date and whether the treaty tie-breaker applies, then prepare the US return and any Form 8833. Gurleen Kaur, CPA (BC and Washington), signs. You get a written quote first.

Moving from other countries

All countries: moving to the US, by country. From Canada: moving from Canada to the US.

Common questions

Am I a US tax resident in my first year after leaving South Korea?

When you meet the green card test or the substantial presence test (31 days this year and 183 weighted days over three years). Your residency starting date is generally your first day in the US that year, or your first day as a permanent resident.

What if I am resident in both South Korea and the US?

Article 3 (Fiscal Domicile) of the treaty breaks the tie, starting with where you have a permanent home. Claiming treaty residence in South Korea on a US return needs Form 8833.

Do I report my accounts in South Korea after moving to the US?

Once you are a US resident, yes: the FBAR when foreign accounts total more than US$10,000, Form 8938 above higher thresholds, and PFIC rules for many foreign funds.

Is there a US social security agreement with South Korea?

Yes, in force since April 1, 2001.

Sources

Every rule and figure on this page links to the IRS, CRA or other official source it comes from. Amounts change; we re-check them before each engagement.

Gurleen Kaur, CPA licensed in British Columbia and Washington State. Last updated November 11, 2026. This page is general information, not tax or legal advice for your situation.

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