Dual Resident? How to Avoid Double Taxation in the US & UK

If you hold citizenship or residency in both the United States and the United Kingdom — or if you have spent enough time in each country to be treated as a tax resident of both simultaneously — you are a dual resident. This situation triggers what many expats fear most: the risk of being taxed twice on the same income. In this guide, we explain exactly how the US and UK define tax residency, what happens when you are resident in both countries at the same time, and how the US-UK Tax Treaty provides the tools to avoid double taxation.

What Makes You a Tax Resident?

US Tax Residency

The United States uses two tests to determine tax residency for non-citizens:

• Substantial Presence Test: You are a US resident for tax purposes if you were present in the US for at least 31 days during the current year and 183 days over a three-year weighted period (100% of current year + 1/3 of prior year + 1/6 of year before that).
• green card Test: Any US lawful permanent resident (green card holder) is treated as a US resident for tax purposes, regardless of where they actually live.

US citizens are taxed on worldwide income regardless of where they live — this is citizenship-based taxation and is unique to the US and Eritrea globally.

UK Tax Residency

The UK uses the Statutory Residence Test (SRT), introduced in 2013. The SRT has three parts:

• Automatic non-residence tests — if you spend fewer than 16 days in the UK (or 46 days if not UK-resident in any of the previous 3 years), you are automatically non-resident
• Automatic residence tests — if you spend 183+ days in the UK, work full-time in the UK, or your only home is in the UK, you are automatically resident
• Sufficient ties test — if neither automatic test applies, residency depends on the number of days in the UK combined with how many “UK ties” you have (family, accommodation, work, 90-day tie, country tie)

How the US-UK Tax Treaty Resolves Dual Residency

When someone is treated as a tax resident of both the US and the UK, Article 4 of the US-UK Income Tax Treaty provides a “tiebreaker” mechanism to determine which country has primary taxing rights. The tiebreaker runs through a hierarchy of tests:

1. Permanent home: The country where you have a permanent home available to you is your country of residence. If you have a permanent home in both countries, go to step 2.
2. Centre of vital interests: The country with which your personal and economic ties are closer. If this cannot be determined, go to step 3.
3. Habitual abode: The country in which you have a habitual abode. If you have a habitual abode in both, go to step 4.
4. Nationality: The country of which you are a citizen (national).
5. Mutual agreement: The competent authorities of both countries must resolve the question by mutual agreement.

Important caveat for US citizens: The US does not recognise the tiebreaker provisions of Article 4 as overriding its citizenship-based taxation. Even if the Treaty tiebreaker places you as a UK resident, the US will still require you to file a return and report worldwide income — though the Treaty benefits (including reduced withholding rates and relief from double tax) still apply.

Key Mechanisms to Avoid Double Taxation

Foreign Tax Credit (FTC)

The Foreign Tax Credit (Form 1116) is the primary tool for dual residents who pay UK income tax. It allows you to offset US tax dollar-for-dollar against foreign taxes already paid on the same income. For UK-based Americans, the UK rate (up to 45%) typically exceeds the US rate (up to 37%), meaning the FTC often eliminates US tax entirely — while the filing obligation remains.

Foreign Earned Income Exclusion (FEIE)

The Foreign Earned Income Exclusion (Form 2555) allows qualifying US expats to exclude foreign earned income up to a threshold (indexed for inflation) from US taxable income. However, the FEIE and the FTC cannot be claimed on the same income — a strategic choice must be made, typically based on your specific income profile, UK tax rate, and retirement account contributions.

Treaty-Based Positions

The US-UK Tax Treaty contains specific provisions governing which country taxes particular types of income — including employment income, business profits, dividends, interest, royalties, capital gains, and pension income. Claiming Treaty benefits on a US return requires filing Form 8833 (Treaty-Based Return Position Disclosure).

Common Dual Resident Scenarios

These are the most common dual-residency situations we handle at US UK Expat Tax Advisors:

• US citizen who has lived and worked in the UK for years — taxed by HMRC on UK income; must also file US returns but typically owes nothing after FTC
• British national who held a US green card and returned to the UK — green card holders remain US tax residents until the card is formally abandoned via Form I-407
• US citizen who splits time between US and UK homes — Substantial Presence Test may create US residency; SRT ties may create UK residency; Treaty tiebreaker and careful day-counting are essential
• non-domiciled UK resident with US citizenship — HMRC remittance basis may be available; must be coordinated carefully with US worldwide reporting requirements

Get Expert Help With Your Dual Residency Position

Dual residency situations are among the most technically complex in international tax. The wrong position can result in double taxation that was entirely avoidable — or missed filings that lead to significant penalties. Our dual-qualified specialists work across both IRS and HMRC frameworks to find the optimal structure for your specific situation.

See also: Cross-Border Tax Planning | US Expat Tax Services | UK Self Assessment