I'm a dual US-Mexican citizen — does that change my tax situation?

What the US sees: citizenship-based taxation

The United States taxes its citizens on all income, wherever it is earned, regardless of where they live. Becoming a Mexican citizen does not remove the obligation to file Form 1040 every year, report wages, interest, dividends, and capital gains from Mexico and everywhere else, and disclose foreign accounts.

Dual citizenship does not unlock any special exclusion either. The relief available to a dual citizen living in Mexico is the same relief available to any US citizen abroad:

• Foreign Earned Income Exclusion (FEIE, Form 2555) — excludes a capped amount of foreign earned income (wages, self-employment) if you pass the bona fide residence or physical presence test. It does not apply to investment income, and you must file to claim it.
• Foreign Tax Credit (Form 1116) — credits Mexican income tax you paid against the US tax on the same income. This is usually the better tool for Mexico because Mexican income tax rates are substantial.

Miss a required filing and the penalty regime is the same as for any American abroad: FinCEN Form 114 (FBAR) is due April 15 with an automatic extension to October 15 for aggregate foreign accounts over $10,000 at any point in the year.

What Mexico sees: residence, not citizenship

Mexico taxes residents on worldwide income and non-residents only on Mexican-source income. Critically, Mexico's residency test is not a simple 183-day rule — a point expat forums get wrong constantly. Under Article 9 of the Código Fiscal de la Federación:

1. If you establish a home (casa habitación) in Mexico, you are a resident.
2. If you also keep a home in another country, Mexico looks at your center of vital interests — for example, where more than 50% of your annual income comes from, or where your principal professional activities are.

In other words, a dual citizen with a house in Guadalajara and most of their income from Mexican sources is a Mexican tax resident even if they spend months in Texas. Mexican individual income tax is progressive, with the top rate reaching 35%.

When both countries claim you: the treaty tie-breaker

If you are a tax resident of both countries, the US–Mexico income tax treaty has its own tie-breaker: permanent home first, then center of vital interests, then habitual abode, then nationality, and only then negotiation between the two tax authorities. The treaty also caps what Mexico (or the US) can withhold on cross-border passive income:

These caps are why treaty claims matter in practice: without the treaty, Mexico's domestic withholding on some of these payments is higher.

Where dual citizenship actually gets complicated

Banking. Mexican banks comply with FATCA, so as a US citizen you will be asked to sign a W-9 and your account data gets reported to the IRS. Mexican bank statements don't come with 1099s, so interest tracking is on you — and Schedule B Part III requires you to name the country of each foreign account.

Succession. A fideicomiso names substitute beneficiaries, and Mexican wills (testamentos) follow local formalities. On the US side, a foreign bequest above the reporting threshold must be reported on Form 3520 Part IV.

Identity paperwork. Dual citizens living in Mexico generally need a CURP and RFC to open accounts, sign contracts, and file with SAT. This is administrative, but it is the step most people discover last.