A child can become a U.S. citizen through a parent in three main ways: at birth abroad to a citizen parent, automatically after birth when certain conditions are met, or through an expedited process for children who live abroad. In many families, a child already is a citizen and only needs proof. In others, a condition is missing and the child needs a different path.
This guide covers each route and the documents that prove the result. Nationality law is highly technical, and the rules that apply depend on the child’s birth date and the parent’s history, so treat this as an orientation rather than an answer for a specific child.
Route 1: Citizenship at birth abroad
A child born outside the United States can be a citizen from birth if a parent was a U.S. citizen and met certain residence or physical presence requirements before the birth. The rules are in section 301 of the INA and, for children born to unmarried parents, section 309. USCIS describes these as acquisition at birth in its Policy Manual summary.
The most common current rule for a child born to one citizen parent and one noncitizen parent in wedlock requires the citizen parent to have been physically present in the United States for at least five years before the birth, at least two of them after age 14. Different rules apply when both parents are citizens, when the parents were not married, and for births under earlier versions of the law.
A child who acquired citizenship at birth does not need to apply to become a citizen. The family needs proof, most often:
- a Consular Report of Birth Abroad, requested at a U.S. embassy or consulate, usually while the child is under 18;
- a U.S. passport; or
- a Certificate of Citizenship from USCIS on Form N-600.
Route 2: Automatic citizenship after birth
The Child Citizenship Act of 2000 created section 320 of the INA. A child born abroad automatically becomes a citizen when all of the following are true before age 18:
- at least one parent is a U.S. citizen, by birth or NaturalizationThe process by which a permanent resident becomes a U.S. citizen, generally after three or five years of residence, by filing Form N-400.See it in the glossary;
- the child is a lawful permanent resident;
- the child is residing in the United States in the legal and physical custody of the citizen parent.
The conditions can be met in any order. A common example is a child who immigrated with a green card and whose parent naturalized while the child was still 17 and living with that parent. In that case, the child became a citizen on the date the last condition was met.
Adopted children can qualify under section 320 if the adoption meets the definitions in the INA, which include age and custody requirements. Stepchildren who were not adopted do not qualify through a stepparent.
Proof for automatic citizenship
Automatic citizenship happens by law, but it is not recorded automatically. Families typically file Form N-600 for a Certificate of Citizenship or apply directly for a U.S. passport with evidence that each condition was met. Keep the parent’s naturalization certificate, the child’s green card, birth certificate, and custody records such as a divorce decree.
What if the child is already 18?
If the conditions were not all met before the 18th birthday, section 320 does not apply. The person generally needs to naturalize on their own, as a permanent resident, once eligible. Our Visa Library comparison of acquired and derivative citizenship explains the difference.
Route 3: Children who live abroad (N-600K)
A child who lives outside the United States, and did not acquire citizenship at birth, cannot use section 320 because they are not residing in the United States. Section 322 of the INA provides a separate, application-based route through Form N-600K. According to USCIS’s N-600K tip sheet, the child must:
- have at least one U.S. citizen parent, including an adoptive parent;
- be under 18;
- reside outside the United States in the legal and physical custody of the citizen parent;
- be temporarily present in the United States after a lawful admission to complete the process; and
- have a citizen parent with at least five years of physical presence in the United States, two after age 14, or a citizen grandparent who meets that requirement.
The application must be approved and the oath taken before the child turns 18. Families need to plan travel to the United States for the interview and oath, which means the child must be admissible and properly admitted, often on a visitor visa.
Children of government employees and service members
USCIS updated its policy in 2019 on children of U.S. government employees and service members stationed abroad, clarifying that living abroad with such a parent does not count as residing in the United States for section 320. Those families generally use the N-600K route. The USCIS fact sheet describes the change.
Birth in the United States
A child born in the United States is a citizen at birth under the Fourteenth Amendment, with narrow exceptions such as children of foreign diplomats. On June 30, 2026, the Supreme Court struck down the Executive orderA directive from the President to federal agencies and officials about how to run the executive branch and carry out the law. Executive orders are numbered and published in the Federal Register, and they generally bind the executive branch.See it in the glossary that tried to narrow birthright citizenship, in Trump v. Barbara. The President signed new executive orders on August 6, 2026 that challengers say again seek to limit it, according to the Asian Law Caucus. We track developments in our coverage of Executive Order 14419.
Common problems
- Missing proof of the parent’s physical presence. School records, tax records, pay stubs and old passports help reconstruct a parent’s years in the United States.
- Custody gaps. Section 320 requires legal and physical custody by the citizen parent. Divorce and custody orders matter.
- Legitimation for children of citizen fathers. Children born to unmarried parents face additional requirements when citizenship passes through the father.
- Age deadlines. Both section 320 and section 322 end at 18.
Why it matters to check
A child who is already a citizen should not apply for a green card or naturalization as if they were not. A person who assumes they derived citizenship when a condition was missing can face serious problems later, such as when voting or applying for federal jobs. Proof settles the question. For how naturalization works for adults, see our naturalization guide.
Common questions
Does a child who derived citizenship need to take an oath?
Not under section 320. Citizenship arrives automatically when the conditions are met. The N-600K route under section 322 is different: it is an application for naturalization, and the child takes an oath if required by age.
Is a Consular Report of Birth Abroad the same as a passport?
No. A Consular Report of Birth Abroad is proof of citizenship for a child who acquired it at birth abroad. A passport is a travel document that also serves as proof of citizenship. Many families obtain both.
What if the citizen parent never lived in the United States?
The child may not have acquired citizenship at birth, because most rules require the citizen parent to have lived or been physically present in the United States before the birth. A grandparent’s physical presence can help in the N-600K process in some cases.
Can a green card holder parent pass citizenship to a child?
Not until the parent becomes a citizen. Once the parent naturalizes, a child under 18 with a green card who lives in the United States in the parent’s legal and physical custody can become a citizen automatically.