Dual Citizenship and U.S. Tax Filing: What the Second Passport Does Not Change

Why the obligation follows the passport

The United States is unusual in taxing on the basis of citizenship rather than residence. A U.S. citizen is subject to tax on worldwide income from all sources and must report all taxable income, and the IRS applies the same filing rules whether the person is in the United States or abroad. Holding a second nationality alongside it does not create an exemption; it simply means two countries have a claim, which is the problem that credits, exclusions and treaties exist to manage.

This catches a particular group hard: people who did not know they were U.S. citizens. Citizenship can pass through a parent, or arise from a birth during a short stay. Someone who has lived their whole life elsewhere can be a U.S. citizen with decades of unfiled returns and no idea of it. That situation has recognised routes back into compliance, covered in the guide on delinquent filing paths.

What is actually due

The deadlines are not the domestic ones

Facts that change the answer

• Which days you were physically present in which country, and whether your tax home was abroad
• Whether your foreign country taxes the same income, and at what rate relative to the U.S. rate
• Whether your income is earned (salary, self-employment) or unearned (dividends, rent, pensions) — the exclusion only reaches earned income
• Whether you hold foreign pensions, foreign mutual funds, or an interest in a foreign company or trust, each of which can add its own information return
• Whether you are married, and to whom — a non-U.S. spouse changes both the filing options and the account reporting
• What has already been filed, and whether the IRS has contacted you about any year

The state you left may still think you live there

Federal tax is only half the picture, and the half that catches returning and departing citizens off guard is the state. States set their own residency rules, and leaving the country is not automatically leaving a state for tax purposes. Some states look at where your domicile is — the place you intend to return to — which can survive years abroad if you kept a home, a driver’s licence, voter registration, or a vehicle there.

This matters more than it sounds, because the reliefs that make the federal return manageable often do not exist at state level. A state may not recognise the foreign earned income exclusion at all, and may not give credit for foreign tax paid in the way the federal system does. It is entirely possible to owe nothing federally and still have a state filing obligation on the same income.

South Carolina residents moving abroad, and people moving to South Carolina from overseas, should treat the state question as a separate piece of work rather than an afterthought — including what was filed, or not filed, in the state during the years abroad.

Common misconceptions

• "I pay tax where I live, so I have nothing to file." Filing and owing are separate. The return is still due.
• "My income is below the exclusion, so there is nothing to do." The exclusion is claimed on a return. It does not apply by itself.
• "The money never entered the United States." Irrelevant to whether it is reportable.
• "No U.S. form was issued, so it is not reportable." Also irrelevant.
• "I reported the account on the FBAR, so Form 8938 is covered." They are different forms filed with different agencies.
• "Renouncing citizenship clears the past." It does not, and expatriation has its own filing and potential exit tax.

When this needs more than a CPA

Bring in a tax attorney, or a specialist, where there is any question of whether past non-filing was deliberate; where the IRS has already made contact about the years concerned; where expatriation is being considered; or where foreign trusts, foreign companies or unfamiliar investment wrappers are involved. Those carry information returns and exposures well beyond an ordinary individual return.