US citizenship through parents is governed by INA §§ 301, 309, 320, and 322, and operates through two distinct mechanisms that are frequently conflated by applicants and even by some practitioners. Acquisition at birth under INA § 301 confers citizenship automatically on a child born outside the United States where the US citizen parent (or parents) meet specific residence requirements that depend on the child's date of birth, the parents' marital status at the time of birth, and whether one or both parents were US citizens. Derivation after naturalisation under INA § 320 (for children in the United States) or INA § 322 (for children living abroad) confers citizenship automatically on a child under 18 who is a lawful permanent resident and who is in the legal and physical custody of a US citizen parent who naturalises (or who is already a US citizen). Both paths produce citizenship without the child ever filing a naturalisation application, but both paths require affirmative documentation through Form N-600 (Application for Certificate of Citizenship) or Form N-600K (for children abroad) to obtain the Certificate of Citizenship that serves as primary evidence of US citizenship. The N-600 filing fee is $1,170 as of 2025, the N-600K fee is $1,170, and processing times range from 6 to 18 months depending on the USCIS field office. The rules changed substantially in 1986, again in 2000 with the Child Citizenship Act, and again in 2008 with technical amendments, so the year of birth and the year of the parent's naturalisation are the two most important facts in any derivation analysis.
Acquisition at birth vs derivation after naturalisation
Acquisition at birth under INA § 301 means the child is a US citizen from the moment of birth, even if the birth occurs outside the United States, provided the US citizen parent (or parents) meet the statutory residence requirements. The child does not need to be admitted as a lawful permanent resident, does not need to live in the United States, and does not need to take any affirmative step to claim citizenship — although obtaining a Consular Report of Birth Abroad (FS-240) at a US embassy or consulate within five years of the birth is the standard way to document the status. Acquisition is determined entirely by the facts at the time of birth: the child's date of birth, the parents' citizenship and marital status at that moment, and the US citizen parent's prior residence in the United States. If those facts satisfy the applicable statute, the child is a US citizen from birth; if they do not, the child is not a US citizen and acquisition cannot be cured later (although derivation may be available if the parent later naturalises).
Derivation after naturalisation under INA § 320 (children in the United States) or INA § 322 (children abroad) means the child becomes a US citizen automatically when certain conditions are met after birth, typically when the parent naturalises. The conditions under § 320 are: at least one parent is a US citizen (by birth or naturalisation); the child is under 18; the child is a lawful permanent resident; and the child is in the legal and physical custody of the US citizen parent and residing in the United States under a lawful admission. The conditions under § 322 (for children living abroad) are: at least one parent is a US citizen; the child is under 18; the child is in the legal and physical custody of the US citizen parent; the US citizen parent has been physically present in the US for at least five years (two after age 14), or the citizen parent has a citizen parent who meets that presence requirement; and the child is temporarily present in the US under a lawful admission. Derivation is not retroactive to birth — the child becomes a citizen when the last condition is met, typically on the date of the parent's naturalisation oath.
| Feature | Acquisition (INA § 301) | Derivation (INA § 320 / § 322) |
|---|---|---|
| Citizenship from | Birth | Date last condition is met (often parent's naturalisation) |
| Statutory trigger | Parents' citizenship, marital status, US residence at time of birth | Parent US citizenship + child LPR + under 18 + legal/physical custody |
| Child must be LPR? | No | Yes (§ 320); no but must be lawfully admitted (§ 322) |
| Child must live in US? | No | Yes (§ 320); no, but temporarily present required (§ 322) |
| Age limit on child | None | Under 18 at time conditions met |
| Documentation form | FS-240 (Consular Report of Birth Abroad) | Form N-600 (§ 320) or Form N-600K (§ 322) |
| Filing fee (2025) | $100 FS-240 consular fee | $1,170 |
Pre-1986 acquisition rules: 10 years, 5 after age 14
For a child born abroad to one US citizen parent and one alien parent before 14 November 1986, the acquisition rule under former INA § 301(a)(7) required the US citizen parent to have been physically present in the United States for at least ten years before the child's birth, at least five of which were after the citizen parent reached age 14. The ten-year total could include time before age 14 (such as childhood residence), but the five-year-after-14 requirement meant that a US citizen parent who left the United States at age 16 could not transmit citizenship to a child born abroad until the parent had accumulated at least three additional years of US residence after age 14 — which often required the parent to return to the US for further study or work. The rule was criticised for being both excessive (a 14-year-old citizen parent with two years of post-14 residence could not transmit) and under-inclusive (a 14-year-old who had lived her entire life in the US could not transmit), and was relaxed in 1986.
For a child born abroad in wedlock to two US citizen parents before 14 November 1986, the rule required only that one of the citizen parents had a residence in the United States at some point prior to the child's birth — a much lighter requirement. For a child born out of wedlock abroad to a US citizen mother, the rule required only that the mother had been physically present in the United States for one continuous year at some point before the birth. The out-of-wedlock father faced a higher bar: until the US Supreme Court's decisions in Miller v. Albright (1998) and Nguyen v. INS (2001), an out-of-wedlock father could transmit citizenship only if he had legitimated the child before the child reached age 21. The current rule for out-of-wedlock fathers under INA § 309(a)(4) requires the father to have been physically present in the US for the periods required by § 301(g) (currently five years, two after age 14), to have agreed in writing to provide financial support until the child reaches 18, and to have acknowledged paternity in writing or had paternity established by adjudication before the child reaches 18.
1986 to 2001: the 5-year, 2-after-14 rule
The Immigration and Nationality Act Amendments of 1986, effective for children born on or after 14 November 1986, relaxed the physical presence requirement for one-citizen-parent births in wedlock from ten years (five after age 14) to five years (two after age 14). The new rule, codified at INA § 301(g), applies to children born between 14 November 1986 and 26 February 2001 (the effective date of the Child Citizenship Act of 2000). A US citizen parent who left the United States at age 18 with three years of post-14 residence could now transmit citizenship, provided the parent had accumulated five years of total physical presence (including the years before age 14). The two-after-14 requirement was retained to ensure that the citizen parent had a meaningful connection to the United States as an adult, but the total reduction from ten years to five was a substantial liberalisation.
The two-citizen-parent rule was also tightened slightly: from 14 November 1986, both citizen parents needed to have a US residence prior to the birth, not just one — a small but significant change that caught applicants by surprise where one citizen parent had been born abroad and never lived in the US. The out-of-wedlock mother's one-year presence requirement was retained without change. The 1986 amendments also introduced the concept of "presence abroad counts as presence in the United States" for certain government employees and military members under INA § 301(b), allowing Foreign Service officers, military members stationed abroad, and certain other government employees to count their overseas service as US physical presence for transmission purposes.
The Child Citizenship Act of 2000 and automatic derivation
The Child Citizenship Act of 2000 (CCA), effective 27 February 2001, fundamentally changed the derivation rules and made citizenship automatic for thousands of children who had previously been LPRs with citizen parents. Under INA § 320, as amended by the CCA, a child under 18 automatically becomes a US citizen on the date that all of the following conditions are met: at least one parent is a US citizen (by birth or naturalisation); the child is under 18; the child is a lawful permanent resident; and the child is residing in the United States in the legal and physical custody of the US citizen parent. There is no application required — the citizenship vests automatically when the last condition is met, typically the date of the parent's naturalisation oath. The child can then apply for a Certificate of Citizenship on Form N-600 ($1,170 fee) or for a US passport ($135 for a minor passport under 16, $100 for ages 16 and 17) as documentation of the citizenship that has already vested.
The CCA applies only to children who were under 18 on or after 27 February 2001 — children who turned 18 before that date are governed by the pre-CCA derivation rules, which were significantly more restrictive. Under the pre-CCA rules (former INA § 321), derivation required: the child to be under 18; a permanent-resident parent to naturalise; the child to be a lawful permanent resident; and either (a) both parents naturalise, (b) the surviving parent naturalises (if the other is deceased), (c) the parents are legally separated and the parent with legal custody naturalises, or (d) the child is born out of wedlock and the mother naturalises. The pre-CCA rules also required the naturalisation to occur before the child turned 18 — a child whose parent naturalised when the child was 19 could not derive citizenship. The CCA's automatic-vesting rule has been applied retroactively only to children who were under 18 on 27 February 2001 — older children are stuck with the pre-CCA rules even if their parent naturalised decades ago.
Forms N-600 and N-600K: certificate of citizenship
Form N-600 (Application for Certificate of Citizenship) is filed with USCIS by a person who is already a US citizen (by acquisition or by derivation) and who wants documentary evidence of that citizenship. The form is filed with USCIS by mail or online, the filing fee is $1,170 as of 2025, and the processing time is typically 6 to 18 months depending on the USCIS field office with jurisdiction over the applicant's residence. The applicant must submit evidence of the citizenship claim: for acquisition, this includes the foreign birth certificate, evidence of the US citizen parent's physical presence in the US (passports, school records, tax returns, employment records), and evidence of the parents' marital status. For derivation under § 320, the applicant submits the child's birth certificate, the parent's Certificate of Naturalisation (or other evidence of US citizenship), the child's permanent resident card, and evidence that the child was residing in the US in the parent's legal and physical custody before age 18.
Form N-600K (Application for Citizenship and Issuance of Certificate Under Section 322) is filed by a US citizen parent on behalf of a child who is living abroad and who qualifies for citizenship under INA § 322. The N-600K must be filed before the child reaches 18, and the child must enter the United States for the USCIS interview while the application is pending — the citizenship vests at the interview, not at filing. The filing fee is $1,170, and the child must be temporarily present in the US under a lawful admission (typically a B-2 visitor visa or the Visa Waiver Program) at the time of the interview. The § 322 process is the only path to US citizenship for a child living abroad who is not an LPR and who has not acquired citizenship at birth, and it requires the US citizen parent (or the citizen parent's own citizen parent) to have the requisite five-year physical presence in the US (two after age 14). The N-600K is the rarer of the two forms, with USCIS receiving approximately 1,500 applications per year compared to approximately 50,000 N-600 applications.
Out-of-wedlock births and the legitimisation rules
The citizenship rules for children born out of wedlock differ significantly from the in-wedlock rules, and the differences have been the subject of substantial constitutional litigation. Under INA § 309(a), a child born out of wedlock abroad to a US citizen mother acquires citizenship at birth if the mother was physically present in the US for one continuous year at any point before the birth — a much lighter requirement than the five-year (two-after-14) rule for in-wedlock one-citizen-parent births. The one-year rule for mothers was upheld by the Supreme Court in Fiallo v. Bell (1977) against an equal-protection challenge, and Congress has not amended the rule despite repeated recommendations. A child born out of wedlock abroad to a US citizen father acquires citizenship at birth only if the father meets the § 301(g) physical presence requirement (five years, two after age 14) and if paternity is established by one of three methods: legitimation under the law of the child's residence or domicile, the father's written acknowledgment of paternity under oath, or court adjudication of paternity — all before the child reaches age 18.
The father must also agree in writing to provide financial support for the child until the child reaches 18. The different requirements for mothers and fathers were challenged in Miller v. Albright (1998) and Nguyen v. INS (2001); the Supreme Court upheld the differential treatment in Nguyen on the grounds that the government has an important interest in ensuring a biological and demonstrable relationship between the citizen parent and the child. The practical consequence is that an out-of-wedlock child of a US citizen father who has not been legitimated, has not had paternity adjudicated, and for whom the father has not executed a written acknowledgment before the child turns 18 cannot acquire citizenship at birth — even if the father's physical presence is sufficient. The father in that situation should consult an immigration attorney promptly after the birth to ensure paternity is established in time.
Case studies
A US citizen mother (born in California in 1985, lived in the United States continuously until age 20 when she moved to Germany for graduate study) gave birth to a child in Berlin in July 2019. The mother was married to a German national at the time of the birth. The child was born in wedlock to one US citizen parent and one alien parent after 14 November 1986, so the applicable rule is INA § 301(g): the citizen parent must have been physically present in the US for at least five years before the birth, at least two of which were after age 14. The mother had lived in the US from birth until age 20, accumulating 20 years of physical presence of which 6 years were after age 14 — comfortably satisfying the rule. The child acquired US citizenship at birth on 12 July 2019, even though the child has never been to the United States.
The mother applied for a Consular Report of Birth Abroad (FS-240) at the US Embassy in Berlin in September 2019, paying the $100 consular fee and submitting her US passport, her California birth certificate, her high school and university transcripts as evidence of US residence, and the child's German birth certificate. The embassy issued the FS-240 in November 2019, and the mother simultaneously applied for a US passport for the child ($135 fee for a minor passport), which was issued in December 2019. The child is now a US citizen with full passport and FS-240 documentation, and the mother did not need to file Form N-600 — the FS-240 is the primary evidence of citizenship for an acquisition case. Total cost: $235 in fees and approximately two months of processing time.
A 12-year-old child born in the Philippines in 2012 entered the United States as a lawful permanent resident in March 2018, sponsored by her father who had naturalised as a US citizen in 2015. At the time of the child's entry, the father was already a US citizen, the child was under 18, the child was an LPR, and the child was residing in the US in the legal and physical custody of the citizen father. Under INA § 320, as amended by the Child Citizenship Act of 2000, the child automatically became a US citizen on 15 March 2018 — the date she entered the United States as an LPR and was admitted at the port of entry. The citizenship vested automatically, without any application being filed, on that date.
The father filed Form N-600 in May 2018 to obtain documentary evidence of the child's citizenship, paying the $1,170 filing fee and submitting the child's Philippine birth certificate, the father's Certificate of Naturalisation, the child's permanent resident card, and evidence of the child's residence in the father's custody. USCIS issued the Certificate of Citizenship in January 2019 after an eight-month processing time. The father also applied for a US passport for the child in July 2018 ($135 fee), which was issued in September 2018. The child did not need to file Form N-400 (naturalisation application) at any point — she was already a US citizen. Total cost: $1,305 in fees and approximately eight months for the Certificate of Citizenship. The child's citizenship vests even if the family never files Form N-600 — the form documents the citizenship, it does not create it.
A US citizen mother was born in California in 1990 to a US citizen father (a native-born American who had lived in the United States his entire life) and moved with her family to Mexico in 2005 at age 15, where she has lived continuously since. She married a Mexican national in 2018 and gave birth to a child in Guadalajara in October 2021. The child was born in wedlock to one US citizen parent and one alien parent after 14 November 1986, so the applicable acquisition rule is INA § 301(g): the citizen parent must have been physically present in the US for at least five years before the birth, at least two of which were after age 14. The mother had lived in the US from birth until age 15 — accumulating 15 years of physical presence but only 1 year after age 14, falling one year short of the two-year requirement. The child therefore did not acquire US citizenship at birth, despite having a US citizen mother and a US citizen grandfather.
The family retained an immigration attorney in January 2022 ($450 consultation fee), who identified that INA § 322 permits a child living abroad to naturalise if the US citizen parent (or the citizen parent's own citizen parent — the child's grandparent) has the requisite five-year physical presence (two after age 14). The child's grandfather met that requirement without difficulty, having lived in the United States continuously from 1945 to 2018. The attorney prepared Form N-600K (Application for Citizenship and Issuance of Certificate Under Section 322) in March 2022, paying the $1,170 filing fee and submitting the child's Mexican birth certificate, the mother's US birth certificate and passport, the grandfather's US birth certificate and passport, and the grandfather's tax returns and employment records evidencing 73 years of US physical presence. USCIS approved the N-600K petition in November 2022 and scheduled the child's naturalisation interview at the USCIS El Paso Field Office for January 2023, when the child was 15 months old.
The family entered the United States on a B-2 visitor visa for the interview, the USCIS officer verified the child's identity and the grandfather's physical presence evidence, and the mother — acting on the child's behalf — took the oath of allegiance on the child's behalf (children under 14 are not required to take the oath). The child was naturalised on 18 January 2023 and was issued a Certificate of Citizenship (Form N-560) at the ceremony. The family applied for a US passport for the child the same week ($135 fee for a minor passport, expedited processing at $60), which was issued in February 2023. Total cost: $1,170 N-600K fee, $135 passport fee, $60 expedite fee, $2,800 in attorney fees for the N-600K preparation and interview attendance, and approximately $1,400 in travel costs for the family's trip from Guadalajara to El Paso — approximately $5,565 in all. The case illustrates that a failed acquisition analysis is not the end of the road, but the § 322 path requires the child to be under 18, requires the child to enter the United States for the interview, and depends on the citizen parent or grandparent meeting the physical presence requirement that the citizen parent alone could not meet.
Common mistakes
- Assuming citizenship without documentation — Many people who acquired or derived US citizenship as children discover the issue only when they apply for a passport, register to vote, or apply for a federal job. Without a Certificate of Citizenship (Form N-600) or a Consular Report of Birth Abroad (FS-240), the person may be unable to prove citizenship and may face difficulties with employment verification, passport issuance, and federal benefits. The safest course is to obtain documentary evidence before it is needed.
- Filing N-400 instead of N-600 — A person who is already a US citizen by acquisition or derivation cannot naturalise — naturalisation is for non-citizens. Filing Form N-400 ($760 paper filing fee) when the applicant is already a citizen wastes the fee and results in a denial. The correct form is N-600 ($1,170 fee) for documentary evidence, not N-400.
- Miscalculating the citizen parent's physical presence — The § 301(g) five-year (two-after-14) presence requirement is calculated as physical presence, not residence. A US citizen parent who lived in the US from birth to age 17 but spent summers abroad has only 14 years of physical presence, not 17 — and the two-after-14 years may not be satisfied. Passports, school records, and tax returns are the primary evidence of physical presence, and gaps in the record can defeat an acquisition claim.
- Missing the § 322 age-18 deadline — Form N-600K under INA § 322 must be filed and the interview must occur before the child reaches 18. Parents who delay filing until the child is 17 years and 10 months are at risk of missing the deadline if processing takes longer than expected. File at least six months before the child's 18th birthday to allow for processing.
- Not establishing paternity for out-of-wedlock fathers before age 18 — An out-of-wedlock child of a US citizen father cannot acquire citizenship at birth unless paternity is established (by legitimation, written acknowledgment, or adjudication) before the child turns 18. Fathers who delay acknowledging paternity or who rely on informal arrangements can permanently lose the ability to transmit citizenship.
- Confusing pre-CCA and post-CCA derivation rules — The CCA's automatic-vesting rule applies only to children who were under 18 on 27 February 2001. Children who turned 18 before that date are governed by the pre-CCA rules (former INA § 321), which required both parents to naturalise (or the surviving parent, or the parent with legal custody). A 19-year-old in 2001 whose father naturalised but whose mother never did cannot derive citizenship and must naturalise independently.
When to consult a professional
Citizenship-through-parents cases are among the most fact-intensive and statute-dependent in US immigration law, and a one-hour consultation with an immigration attorney ($250 to $500) can identify issues that the applicant would not have spotted. Consultation is strongly recommended where any of the following apply: the child was born before 14 November 1986 (the pre-1986 ten-year rule applies and is stricter); the child was born out of wedlock (the § 309 rules apply and paternity establishment is critical); the citizen parent's physical presence in the US is uncertain or interrupted; the parents divorced or separated before the child turned 18 (the legal custody requirement is critical for derivation); or the child was adopted (adoption-based citizenship under INA § 320 has additional requirements including the two-year legal custody and residence requirement).
Attorneys also assist with the documentation strategy — whether to file Form N-600, Form N-600K, an FS-240 application at a consulate, or simply a passport application — and with the evidentiary record. The passport application is cheaper ($135 for a minor passport) and faster (typically 6 to 8 weeks) than the N-600 (6 to 18 months, $1,170), but the passport can be lost or expired, while the Certificate of Citizenship is permanent primary evidence. For more on the broader citizenship framework, see our green card to citizenship timeline, our N-400 timeline, and try our US citizenship physical presence calculator to verify the parent's presence record before filing.
Frequently asked questions
It depends on whether you meet the physical presence requirements of INA § 301(g). If your child was born in wedlock to you (the US citizen) and an alien spouse, you must have been physically present in the US for at least five years before the child's birth, at least two of which were after you reached age 14. If you meet that requirement, your child acquired US citizenship at birth and you should apply for a Consular Report of Birth Abroad (FS-240) at the nearest US embassy or consulate. If you do not meet the physical presence requirement, your child is not a US citizen at birth — but you may be able to sponsor the child for an immigrant visa and the child can derive citizenship under INA § 320 when admitted as an LPR.
No, but it is strongly recommended. The citizenship vested automatically when the last condition was met (typically the date of admission as an LPR or the date of the parent's naturalisation oath), and you do not need to file any form for the citizenship to take effect. However, the Certificate of Citizenship issued on Form N-600 is the most permanent and authoritative documentary evidence of US citizenship — it cannot be lost or expired like a passport, and it is accepted as proof of citizenship for all federal purposes. The filing fee is $1,170 and the processing time is 6 to 18 months, but the certificate lasts a lifetime.
No. The Child Citizenship Act of 2000 applies only to children who were under 18 on or after 27 February 2001 — the effective date of the Act. If you turned 18 before that date, you are governed by the pre-CCA derivation rules under former INA § 321, which required both parents to naturalise (or the surviving parent, or the parent with legal custody) before you turned 18. Many people in this situation discover that they are not US citizens despite having a naturalised parent — and must naturalise independently on Form N-400 if they are LPRs.
For more on the broader citizenship framework, see our green card to citizenship timeline, our N-400 timeline, our physical presence guide, and try our US citizenship physical presence calculator.
Last reviewed July 7, 2026. This article is informational and does not constitute legal, tax, or financial advice. Consult a qualified professional for guidance specific to your situation.