Two facts decide whether the child is a citizen: were the parents married at the birth, and did the U.S.-citizen parent live in the U.S. long enough? Here is exactly what the law requires.
U.S. citizenship law gives citizenship at birth to certain children born abroad to U.S.-citizen parents — this is called acquisition of citizenship. For a child born outside the U.S. to one U.S.-citizen parent and one non-citizen parent, the citizen parent must have spent enough time physically in the United States before the child was born to be able to “transmit” citizenship.
If the U.S.-citizen parent meets the test, the child is a citizen from birth. The paperwork (CRBA / N-600 / passport) just proves it.
If the U.S.-citizen parent falls short, citizenship can still come later — through a grandparent (N-600K) or a green card (Child Citizenship Act).
Two common questions, answered up front — because they change how you read everything below.
U.S. citizenship-transmission law is completely sex-neutral as to the child. Every rule on this site applies identically to a son or a daughter.
Married parents: no difference — the same physical-presence test applies either way. Unmarried parents: it does matter — see the two variants below.
If the parents were married, just read the married-parents rule and treat “the U.S.-citizen parent” as either mother or father. The mother-vs-father distinction only appears when the parents were unmarried.
For a child born abroad on or after November 14, 1986 to one U.S.-citizen parent, the citizen parent must have been:
Documenting these years is the single biggest task in the whole case. See acceptable physical-presence evidence →
The exact amount of presence depends on when the child was born, because the law changed over time. The two modern brackets:
| Child’s date of birth | U.S.-citizen parent’s required U.S. physical presence | After age 14 |
|---|---|---|
| On/after Nov 14, 1986 | 5 years total | At least 2 years |
| Dec 24, 1952 – Nov 13, 1986 | 10 years total | At least 5 years |
Most families using this guide fall in the first row. If the child was born before late 1986, use the second row and confirm the details with the State Department, since older cases have additional nuances. (An unmarried U.S.-citizen mother has a separate, lighter rule — see below.)
Source: U.S. Dept. of State — Acquisition of U.S. Citizenship by a Child Born Abroad.
This is the simpler case, and it works the same whether the U.S. citizen is the mother or the father. When the parents were legally married to each other when the child was born, only three things matter:
If those hold, the child acquired citizenship at birth. Proceed to the CRBA (under 18) or N-600 (any age).
This is the one place where it matters whether the U.S. citizen is the father or the mother. Pick the variant that fits.
When citizenship is claimed through an unmarried father, the same physical-presence test applies (5 years / 2 after 14) — plus the additional INA 309(a) conditions. All must be satisfied, and the last three before the child turns 18:
A higher standard than usual. Documents establishing paternity, or DNA testing when the embassy requests it. Getting the father named on the PSA birth certificate strongly helps.
Proven by the father’s U.S. passport, birth certificate, or naturalization certificate.
Unless deceased, the father must agree in writing to financially support the child until age 18 — captured on Form DS-2029 / DS-5507 before the consular officer.
Before the child turns 18, one of: legitimation under local law (e.g., the parents’ later marriage), the father’s written, sworn acknowledgment of paternity, or a court paternity order. The child must be unmarried at that time.
If the legitimation/acknowledgment and support steps are not completed before the child turns 18, the child generally does not acquire citizenship at birth — and the case shifts to the immigrant-visa route. Act early.
When citizenship is claimed through an unmarried mother, the rule is generally simpler — there is no legitimation, written-acknowledgment, or support-agreement requirement (maternity is established by the birth itself). Only the physical-presence requirement matters, and it depends on the date of birth:
| Child’s date of birth | Unmarried U.S.-citizen mother’s required presence |
|---|---|
| Before June 12, 2017 | 1 year of continuous physical presence in the U.S. before the birth |
| On/after June 12, 2017 | 5 years total, 2 after age 14 (same as everyone else) |
In Sessions v. Morales-Santana (June 12, 2017), the Supreme Court held that giving unmarried mothers an easier rule than fathers was unconstitutional. Rather than extend the easy rule to fathers, the Court “leveled down” — applying the standard 5-year requirement to children of unmarried U.S.-citizen mothers going forward. The old 1-year rule still covers births before that date.
Sources: USCIS Policy Manual Vol. 12, Pt. H, Ch. 3 (INA 301 & 309) · Sessions v. Morales-Santana, 582 U.S. 47 (2017) · Congressional Research Service R47223.
If the child did not become a citizen at birth, two statutes still lead to citizenship before they turn 18:
A child becomes a citizen automatically once they have a U.S.-citizen parent, are under 18, are a green-card holder, and live in the U.S. in that parent’s custody.
How it worksA child abroad gets citizenship using a U.S.-citizen parent or grandparent’s physical presence — but must travel to the U.S. for the oath.
How it works