No, not automatically. Whether you are a U.S. citizen when one parent is a citizen depends on where you were born, whether your parents were married at the time, and how much time your citizen parent spent living in the United States before your birth. If you were born on U.S. soil, the Fourteenth Amendment makes you a citizen regardless of your parents’ status. If you were born abroad, citizenship passes through the parent’s bloodline only when the specific requirements in federal law are met on your date of birth.
Born in the U.S. vs. Born Abroad
A child born inside the United States is a citizen at birth based on place of birth. The rest of this article is about the harder case: a child born outside the United States to a U.S. citizen parent. That situation runs on a different legal principle, sometimes called jus sanguinis, and the rules turn on a single gatekeeping issue.
That issue is physical presence. The citizen parent has to have actually lived in the United States or its territories for a minimum number of years before the child’s birth. How many years depends on the family’s circumstances. If the parent spent most of their life abroad and cannot document enough time on U.S. soil, the child does not acquire citizenship at birth, even though the parent is a citizen.
One more thing worth knowing up front: the rules have changed over the decades. The version of the law that applies to any given child is the version in effect on that child’s date of birth.
Married Parents, One a U.S. Citizen
If your parents were married when you were born and only one of them was a U.S. citizen, the citizen parent had to have been physically present in the United States for at least five years before your birth. At least two of those five years must have been after that parent turned 14. The five years do not need to run consecutively.1Office of the Law Revision Counsel. 8 US Code 1401 – Nationals and Citizens of United States at Birth
This is where many families discover they have a problem. A citizen parent who left the U.S. as a teenager and lived abroad since often has not accumulated enough qualifying time. Proving the years usually means piecing together school records, tax returns, and travel history.
If both married parents were U.S. citizens, the standard drops dramatically: only one of them needs to have lived in the United States at any point before the birth, with no minimum number of years.1Office of the Law Revision Counsel. 8 US Code 1401 – Nationals and Citizens of United States at Birth
Unmarried U.S. Citizen Mother
For a child born outside marriage to a citizen mother, the rule depends on the child’s date of birth. For decades the mother needed only one continuous year of physical presence in the United States before the birth. That changed with the Supreme Court’s decision in Sessions v. Morales-Santana on June 12, 2017, which held that giving unmarried mothers an easier standard than unmarried fathers violated equal protection. The Court applied the stricter five-year rule to both parents going forward rather than extending the shorter rule to fathers.2Supreme Court of the United States. Sessions v. Morales-Santana, 582 US 47 (2017)
So the practical split is:
- Child born before June 12, 2017: the mother needed one continuous year of physical presence in the United States before the birth.
- Child born on or after June 12, 2017: the mother must meet the same five-year requirement, with two years after age 14, that applies to married couples with one citizen parent.3U.S. Department of State. Obtaining US Citizenship for a Child Born Abroad
Unmarried U.S. Citizen Father
An unmarried citizen father must meet the same five-year physical presence rule (two years after age 14), and he also has to legally establish the parent-child relationship. Physical presence alone is not enough.4Office of the Law Revision Counsel. 8 USC 1409 – Children Born Out of Wedlock
Before the child turns 18, the father must establish a blood relationship (DNA testing is accepted when documents are insufficient), agree in writing to provide financial support until the child is 18, and legally establish paternity by legitimating the child under applicable law, acknowledging paternity in writing under oath, or obtaining a court order. All three items have to be done while the child is still a minor. If the 18th birthday passes without them, the child cannot acquire citizenship through the father under this provision.3U.S. Department of State. Obtaining US Citizenship for a Child Born Abroad
Credit Toward Physical Presence
Two provisions can rescue a case that looks short on years.
The first is for military and government families. Time a citizen parent spends abroad while honorably serving in the Armed Forces, working for the U.S. government, or working for a qualifying international organization counts as if the parent were in the United States. The same credit extends to a citizen parent who spent part of their own youth abroad as the unmarried dependent child of a service member or government employee. For someone who grew up on overseas bases, that can be the difference between qualifying and not.5U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 12 Part H Chapter 3 – US Citizens at Birth (INA 301 and 309)
The second is a grandparent substitute. Under Section 322 of the Immigration and Nationality Act, if the citizen parent cannot meet the physical presence requirement, a U.S. citizen grandparent’s time in the country can be used instead, as long as the grandparent meets the same five-year, two-years-after-14 standard. The child must be under 18, unmarried, living outside the United States, and in the legal and physical custody of the citizen parent, and must be temporarily present in the U.S. in lawful status when the application is approved so the child can take the Oath of Allegiance. The application is Form N-600K. If the citizen parent has died, a citizen grandparent or legal guardian can still file within five years of the parent’s death.6U.S. Citizenship and Immigration Services. Form N-600K Instructions for Application for Citizenship and Issuance of Certificate Under Section 322
What If You Didn’t Qualify at Birth
A child who did not acquire citizenship at birth can still become a citizen later through a process called derivation. Under the Child Citizenship Act of 2000, which took effect February 27, 2001, a child born abroad becomes a U.S. citizen automatically when all of the following are true at the same time:
- The child is under 18 and unmarried.
- At least one parent is a U.S. citizen.
- The child is a lawful permanent resident (green card holder).
- The child lives in the United States in the legal and physical custody of the citizen parent.
Once every condition is met, citizenship happens by operation of law. No separate application is needed for the citizenship itself, though you will still want to obtain documentation. If any condition is not satisfied before the child turns 18, derivation does not happen.7Office of the Law Revision Counsel. 8 USC 1431 – Children Born Outside the United States and Lawfully Admitted for Permanent Residence
Internationally adopted children can derive citizenship under the same framework once they are lawful permanent residents living in the citizen parent’s custody, with the details depending on the visa the child entered on and whether the adoption was finalized abroad.
How Divorce Affects Derivation
Because derivation requires the child to be in the legal and physical custody of the citizen parent, divorce and separation can complicate things. USCIS looks at the most recent court order. Primary custody with the citizen parent satisfies the requirement; joint custody also works; sole custody is not required. If the decree is silent on custody and state law does not automatically assign it, USCIS will accept evidence that the child was actually living with the citizen parent without objection from the other parent, such as school enrollment, medical records, or bank statements showing the child’s address. Private custody agreements between the parents generally do not satisfy the requirement on their own.8U.S. Citizenship and Immigration Services. USCIS Policy Manual – Automatic Acquisition of Citizenship After Birth (INA 320)
How to Prove You’re a Citizen
Being a citizen as a matter of law and being able to prove it are two different things. Three documents work as official proof for someone born abroad:9U.S. Department of State. Get Citizenship Evidence for a US Passport
- A Consular Report of Birth Abroad (CRBA), issued by the U.S. embassy or consulate in the country of birth. This is the standard document for children who acquired citizenship at birth.
- A Certificate of Citizenship, issued by USCIS, typically used by people who derived citizenship after birth or never received a CRBA.
- A U.S. passport, which the State Department issues and which serves as both proof of citizenship and a travel document.
A CRBA is applied for at the embassy or consulate where the child was born. It requires an in-person appointment and costs $100. You’ll need the child’s foreign birth certificate, proof of the parent’s citizenship, the parents’ marriage certificate if applicable, and evidence of the citizen parent’s physical presence in the United States. Physical presence is usually the hardest part to document; school transcripts, W-2s, military records, CBP entry and exit records, expired passports with U.S. entry stamps, and even bank or credit card statements showing U.S. transactions can all help. CRBAs are only available for children under 18. Adults who never received one need to apply for a passport or a Certificate of Citizenship instead.3U.S. Department of State. Obtaining US Citizenship for a Child Born Abroad
The Certificate of Citizenship is applied for on Form N-600, filed online or by mail with USCIS.10U.S. Citizenship and Immigration Services. N-600 Application for Certificate of Citizenship The filing fee is $1,385 for paper applications and $1,335 for online filing, and USCIS updates its fee schedule periodically. Supporting documents include birth certificates, proof of the parent’s citizenship, and evidence of physical presence or the child’s lawful permanent resident status. In fiscal year 2025 the median processing time for N-600 applications was roughly three months, with a meaningful share of cases taking longer.11U.S. Citizenship and Immigration Services. Historical Processing Times If you need proof quickly, applying for a U.S. passport is often faster and counts as equally valid documentation.