US Expat Taxes Explained: How to Avoid Double Taxation with FTC, Treaties & Dual-Status Rules

Why This Question Is More Nuanced Than It Looks

You moved to the US two years ago. You still receive dividends from a home-country brokerage account, a modest pension payment from a former employer, and interest on a savings account you never closed. Each of those income streams may be taxed by the US, and, depending on where it comes from, it may also be taxed by the home country. So which country gets paid first, and how do you avoid paying twice?

That is what the cross-border income-tax toolkit is designed to solve. In my work with expats who have been US tax residents for a few years, I find three tools come up again and again: the Foreign Tax Credit, treaty-based positions filed on Form 8833, and the rules that govern the arrival and departure tax years, the dual-status year. Each does a different job, and getting them confused is one of the most common sources of over-payment and missed filings I see. This article explains what each tool does, when each one actually applies, and the questions worth raising with a qualified cross-border tax preparer.

{{INSET-CTA-1}}

1. The Three Tools, and When Each One Actually Applies

Most double-taxation problems for expats living in the US are solved by one of three mechanisms. Each is set out in the Internal Revenue Code, in a bilateral tax treaty, or in the regulations that govern the year you became or ceased to be a US tax resident.

The Foreign Tax Credit (FTC), under §901 of the Internal Revenue Code, is the default backstop. If a foreign country taxed the income and the US also taxes it, the FTC gives you a dollar-for-dollar credit for the foreign tax, subject to limits. It is claimed on Form 1116 for individuals and does the heavy lifting for most passive income streams.

Treaty-based positions come in when a specific article of a bilateral treaty produces a different result than the default Code rule, reducing withholding rates, reallocating taxing rights, or preserving the tax-favoured status of home-country retirement accounts. When a treaty position is relied upon, it is disclosed on Form 8833 with the return.

Dual-status rules govern the arrival year and the departure year. In those two calendar years the tax calculation splits: income received during the nonresident portion is taxed under non resident rules; income received during the resident portion is taxed under resident rules, including worldwide reporting. In most years after arrival, the FTC and selected treaty positions are the only two tools in play, dual-status is a transitional-year issue.

2. the Foreign Tax Credit (§901): Mechanics and Why It Often Under-credits

The FTC is conceptually simple: if a foreign country taxed foreign-source income that the US is also taxing, the foreign tax can be credited against the US liability on that same income. In practice, three features regularly cause the credit to fall short of a full offset.

First, the credit is computed separately within categories, the "separate limitation" buckets. The main ones for individuals are passive category income (dividends, interest, capital gains, rent, most royalties) and general category income (wages and active business income). Foreign taxes in one category cannot be used to offset US tax in another. Second, the credit is capped at the US tax that would otherwise be payable on that foreign-source income; excess credits can be carried back one year or forward up to ten, within the same category.

Third, source rules matter more than many taxpayers expect. The US sources dividends to the country of incorporation of the paying corporation, interest generally to the residence of the payer, and employment income to where the work was performed. A home-country dividend is usually foreign-source; interest from a foreign bank account is usually foreign-source; but a gain on securities held personally is generally US-source once the taxpayer is a US resident, which can push a capital gain outside FTC eligibility even if the home country also taxed it, a situation where a treaty position may be the better tool than §901 alone.

3. Treaty-based Positions and Form 8833: When Two Countries Both Try to Tax You

Bilateral income-tax treaties exist precisely because source rules and residency rules do not always align. When a taxpayer relies on a treaty position that modifies the default Code outcome by more than a de minimis amount, the reliance is disclosed on Form 8833, filed with the US return.

Three treaty positions come up most often for expats who are already US tax residents. The first is the residency tiebreaker. Some taxpayers meet the residency definitions of both the US and another country simultaneously. Most US treaties contain a tiebreaker test, permanent home, centre of vital interests, habitual abode, nationality, under which the taxpayer is treated as a tax resident of only one country. US green-card holders should note that relying on a tiebreaker to be treated as a foreign resident may affect their immigration status.

The second is pension and retirement-account articles. Many US treaties preserve the tax-favoured growth status of a home-country retirement plan while the taxpayer is a US resident, and address how distributions are taxed. These provisions are explored in more detail in the flagship retirement-account article.

The third is reduced with holding on cross-border dividends, interest, and royalties. Treaties typically cap withholding rates below the domestic rate of the source country. Claiming the reduced rate on inbound US-source payments to a foreign person is done via FormW-8BEN with the payer; claiming reduced home-country withholding usually requires a form filed with the home-country payer. The credit mechanics under§901 in the US then run off the final, treaty-reduced foreign tax, not the pre-treaty rate.

4. Dual-status Years: How the Arrival and Departure Years Actually Work

The calendar year in which a taxpayer becomes a US tax resident, and the calendar year in which they cease to be one, are dual-status tax years. During the nonresident portion, the taxpayer is taxed only on US-source income and on income effectively connected with a US trade or business. During the resident portion, the taxpayer is taxed on worldwide income.

Mechanically, a dual-status filing splits income between the two portions of the year. Dual-status filers generally cannot use the standard deduction, cannot file jointly with a spouse without a specific election, and face tighter rules on many deductions. Elections are available in certain circumstances, for example, a first-year election to be treated as a resident for the full year, or the election for a nonresident spouse of a US citizen to be treated as a resident, each of which changes the mechanics and has its own eligibility rules.

The departure year operates on the same principle in reverse. For long-term green-card holders and US citizens, the departure year may also trigger the §877A expatriation rules, a separate regime covered in Article 23 of this series. In my experience, the arrival-year and departure-year calculations are where cross-border taxpayers most often over-pay, over-report, or miss an available election. Both years warrant a specialist preparer, not general-practice software.

5. Income-type Mechanics: Dividends, Interest, Pensions, Rental, and Capital Gains

Once the taxpayer is a steady-state US resident (neither arrival nor departure year), the question for each foreign income stream is the same: what is the default US treatment, what does the home country do, and does a treaty article change either answer?

Foreign dividends from a home-country brokerage are generally taxable in the US as ordinary dividend income, though some may meet the qualified-dividend definition if the foreign corporation is in a treaty country. Foreign interest is generally fully taxable in the US as ordinary income. For both, home-country withholding is typically reduced by treaty, and the post-treaty foreign tax is claimed via the FTC.

Home-country pensions are a specialised area, their taxation depends heavily on the specific treaty article and the type of plan. See Article 29 for the detailed framework. Foreign rental income is reported on Schedule E, with foreign residential property depreciated straight-line over 30 years under the alternative depreciation system; home-country tax is typically creditable via the FTC. See Article 28 for the full mechanics.

Foreign capital gains on non-PFIC securities are taxed under standard US long- or short-term rules, using the pre-arrival step-up basis rule covered in Article 27 where applicable. Because US residents are generally treated as selling from a US-source perspective, some home-country taxes on these gains may not be fully creditable, source rules and any applicable treaty article both matter here. Finally, many home-country mutual funds and ETFs are treated as PFICs regardless of the toolkit above, and PFIC mechanics override the ordinary credit-and-treaty framework entirely, covered in Article 26.

Source: Skybound 2026

Questions To Raise With A Qualified Adviser

For an expat already tax-resident in the US, a few focused questions tend to surface most of the open items in the cross-border income-tax toolkit:

• Which of my foreign income streams is the FTC fully absorbing, and where is it falling short because of source or category rules?
• Are there treaty articles I should be relying on, and have the disclosures on Form 8833 been made where required?
• If I arrived or am planning to depart the US in a given tax year, which dual-status elections are available and what are their trade-offs?
• Do any of my home-country investments trigger the PFIC regime, which would override this toolkit entirely for those holdings?
• How does my specific bilateral treaty handle my home-country pension, is it recognised, and how are distributions taxed?