Can you keep your Thailand citizenship when you become a U.S. citizen?
Allowed
Yes, in general
Thai citizens who acquire another nationality, including U.S. citizenship, are generally permitted to retain their Thai citizenship.
What the law says
- Under current Thai law, individuals who acquire a foreign nationality after birth are generally permitted to retain their Thai citizenship without issue.
- Thai citizenship is retained unless the individual formally submits a request to renounce it.
- Section 14 merely allows a one-year window after the 20th birthday for those wishing to renounce Thai nationality; there is no legal requirement to choose and no penalty for keeping both.
- Thai citizenship may be revoked in certain cases, such as making a false declaration in an application, using a foreign passport to enter or conduct legal matters in Thailand, residing outside Thailand for more than five years without maintaining domicile, activities harmful to national security or public order, or retaining the nationality of a state at war with Thailand.
“acquire a foreign nationality after birth are generally permitted to retain their Thai citizenship without issue”
What about the U.S. side?
The United States allows dual citizenship. At the oath ceremony you promise to renounce allegiance to other countries, but U.S. law does not make you formally give up your other passport. The question is only whether Thailand lets you keep yours.
Source: Thai nationality law (Wikipedia, summarized on 2026-11-11). Laws change — confirm with the Thailand embassy or consulate before your oath ceremony. This is not legal advice.
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