Dual nationality does not automatically cancel U.S. citizenship
The United States recognizes that a person may hold more than one nationality. Under modern U.S. law, performing a potentially expatriating act is not enough by itself: loss of U.S. nationality requires voluntariness and an intention to relinquish U.S. nationality.
You can be a U.S. citizen and another country's national
The Department of State expressly explains that a person may be a dual or multiple national through birth, parentage, or naturalization. Whether another country permits or recognizes multiple nationality is a question of that country's law.
Dual nationals can have obligations in both countries, including tax, military-service, registration or travel requirements under the relevant laws.
U.S. passport rule
The State Department states that U.S. citizens, including dual nationals, must enter and depart the United States using a U.S. passport. A U.S. citizen is not eligible for a U.S. visa or ESTA using another nationality.
State Department dual-nationality guidancePotentially expatriating acts under 8 U.S.C. § 1481
The statute lists acts that can support a loss-of-nationality determination when the statutory conditions are met. State administers INA 349(a)(1)–(5); DHS administers (a)(6)–(7).
Naturalizing in a foreign state on one’s own application after age 18.
Taking an oath or other formal declaration of allegiance to a foreign state after age 18.
Serving in specified circumstances in the armed forces of a foreign state.
Accepting specified foreign-government employment.
Formally renouncing U.S. nationality before a U.S. diplomatic or consular officer abroad.
Formally renouncing in the United States under the narrow wartime provision.
Certain treason-related conduct after conviction under the statute.
Intent matters
The State Department summarizes the Supreme Court rule from Afroyim v. Rusk and Vance v. Terrazas: U.S. nationality cannot be lost without voluntary relinquishment. Foreign naturalization, a foreign oath, or another listed act therefore requires an intent analysis rather than an automatic-loss assumption.
State Department citizenship law and policyRenunciation is a serious legal act
Formal renunciation abroad under INA 349(a)(5) requires an in-person process before a U.S. diplomatic or consular officer. State currently describes a process including review of loss-of-nationality information, two interviews with at least one in person, required forms, and the prescribed oath.
A Certificate of Loss of Nationality, once approved, is a final administrative determination subject only to the available review routes. Renunciation can create statelessness and does not automatically erase tax, military, criminal or financial obligations.