For people relocating from Ireland to the United States

Moving to the US From Ireland: Your First US Tax Year

Before your first US tax return after leaving Ireland, three questions matter: when you became resident, whether the treaty makes you resident somewhere else, and what to report from Ireland.

Substantial presenceGreen card testDual-status yearTie-breakerSocial security

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Quick answer

When does someone moving from Ireland 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 Ireland, Article 4 (Residence) 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 4 (Residence)
Social security agreement: Yes, since September 1, 1993
Accounts in Ireland: FBAR, Form 8938 and PFIC rules can apply once resident

The residency starting date

Expect your first year to have two halves. Income from Ireland 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 Irish salary, bonuses and investment income the IRS sees.

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 Ireland all go through the same two tests; some visa holders can exclude days. Try the calculator.

Dual residence with Ireland

The US tests in Pub 519 do not override a treaty's own residence rules (IRS Pub 519). For people moving from Ireland: Article 4 (Residence) 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.

Reporting what you keep abroad

Do not close everything in Ireland in a hurry, and do not forget it either. As a US resident you report foreign accounts on the FBAR and Form 8938 when they pass the thresholds, and many investment funds bought in Ireland fall under the PFIC rules (IRS). Details: FBAR and FATCA; Form 8938.

Sources for moving from Ireland

Treaty

The IRS lists the 1997 income tax treaty, signed July 28, 1997, amended by an amending convention listed for 1999. General effective date (IRS Table 3): treaty Jan. 1, 1998 (IRS treaty documents for Ireland; treaty text; IRS Table 3).
Residence and tie-breaker: Article 4 (Residence).
Saving clause: Article 1 (General Scope).
Article 18 (Pensions, Social Security, Annuities), pensions.
Article 24 (Relief from Double Taxation), relief from double taxation.
Article 15 (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 Ireland on leaving the country also apply; check them with a local adviser.

How we help

Send us your arrival date, visa or green card dates and a summary of income and accounts in Ireland. We confirm your US status for the year, prepare the dual-status or resident return with the reporting it needs, and Gurleen Kaur, CPA licensed in British Columbia and Washington State, signs. Quote before any work.

Common questions

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

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 Ireland and the US?

Article 4 (Residence) of the treaty breaks the tie, starting with where you have a permanent home. Claiming treaty residence in Ireland on a US return needs Form 8833.

Do I report my accounts in Ireland 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 Ireland?

Yes, in force since September 1, 1993.

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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