Will I lose my original citizenship if I naturalize as a U.S. citizen?

The Oath of Allegiance taken at the naturalization ceremony includes a renunciation of "all allegiance and fidelity to any foreign prince, potentate, state, or sovereignty." That language is symbolic, not operative under U.S. law: the State Department has long held (see 7 FAM 1200) that the U.S. does not require a naturalized citizen to formally renounce other citizenships, and dual citizenship is fully recognized.

What the United States actually cares about

• You owe primary allegiance to the United States. That means using your U.S. passport for U.S. entry, paying U.S. taxes on worldwide income, and complying with U.S. military registration where applicable.
• You may serve in a foreign military or accept foreign employment without losing U.S. citizenship, unless you do so with intent to relinquish U.S. citizenship (the Vance v. Terrazas standard).

What your country of origin may do

The rules vary widely:

• Mexico — permits dual nationality and does not revoke Mexican nationality upon U.S. naturalization (since the 1998 constitutional amendment).
• El Salvador, Guatemala, Honduras, Colombia, Peru, Ecuador, Argentina, Chile, Brazil — all permit dual nationality.
• India — does not permit dual citizenship, but offers Overseas Citizen of India (OCI) status which provides most practical benefits.
• China (PRC) — does not recognize dual nationality; voluntary naturalization elsewhere triggers loss of PRC nationality, but enforcement is inconsistent.
• Philippines — permits dual nationality (Republic Act 9225) for those who acquired foreign citizenship through naturalization.
• Vietnam, Japan, South Korea, Singapore — generally do not permit dual citizenship for adults, though exceptions exist.

The practical tax issue

U.S. citizens are taxed on worldwide income under the Internal Revenue Code, regardless of residence. A dual citizen living abroad still files U.S. returns (often with foreign earned income exclusion and foreign tax credits to avoid double taxation). The FBAR (FinCEN Form 114) and FATCA Form 8938 disclosure obligations also apply. New citizens should expect to file U.S. returns indefinitely.

Travel as a dual citizen

• Enter and exit the U.S. on your U.S. passport. Required under 22 C.F.R. § 53.1.
• Enter and exit your other country on that country's passport where it is required.
• Many dual citizens carry both passports on every trip.

How we handle this

For clients who care about the dual-citizenship analysis we provide a country-specific briefing before filing the N-400, citing the home-country statute and consular practice. Where the home country has formal revocation rules, we coordinate with home-country counsel so the client can decide knowingly. The Oath itself is straightforward; the consequences abroad are where attention is needed.