Naturalization

Date of Information: 09/23/2026

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Naturalization is the legal process through which a person who was not a U.S. citizen at birth becomes one. For most applicants, it follows a period of lawful permanent residence and ends when the applicant takes the Oath of Allegiance. Before starting that process, however, a person should determine whether they already acquired citizenship at birth or automatically became a citizen through a parent. In that situation, the task may be to document existing citizenship rather than apply to become a citizen. 8 U.S.C. §§ 1431, 1433; USCIS Policy Manual, Volume 12.

Constitutional Basis for Naturalization

Article I, Section 8, Clause 4 of the Constitution authorizes Congress to establish “an uniform Rule of Naturalization.” That provision gives Congress the authority to set nationwide rules under which noncitizens may become citizens. States cannot create their own competing routes to U.S. citizenship. Congress has exercised this power principally through the Immigration and Nationality Act (INA), while assigning most individual naturalization decisions to U.S. Citizenship and Immigration Services (USCIS). U.S. Constitution, Article I, Section 8; Constitution Annotated, Naturalization Clause; USCIS Policy Manual, USCIS Authority to Naturalize.

Congress’s authority to prescribe naturalization rules does not mean that every question of citizenship is left to Congress. The Fourteenth Amendment itself declares that people born or naturalized in the United States, and subject to its jurisdiction, are citizens of the United States and of the state where they reside. Congress also enacts statutes addressing citizenship acquired at birth outside the United States through a U.S. citizen parent. These are distinct legal routes to citizenship, with different requirements and methods of proof. U.S. Constitution, Fourteenth Amendment; Constitution Annotated, Citizenship Clause.

A Brief History of Naturalization

Congress enacted its first naturalization statute in 1790. It permitted certain “free white” immigrants to naturalize after two years of residence. Later statutes changed the residence period and procedures; an 1870 law extended naturalization eligibility to people of African descent. The early laws were explicitly discriminatory, and eligibility changed over time as Congress revised racial and other restrictions. Constitution Annotated, Early U.S. Naturalization Laws.

For much of U.S. history, naturalization took place in courts. Before 1906, state, local, and federal courts could grant citizenship under federal law, with limited federal oversight and inconsistent records. The Basic Naturalization Act of 1906 introduced federal supervision and standardized documentation. The Nationality Act of 1940 reorganized nationality law, and the Immigration and Nationality Act of 1952 became the foundation of the statute used today, as subsequently amended. In October 1991, responsibility for most naturalization decisions shifted from federal courts to the federal immigration agency; USCIS now performs that administrative role. National Archives, Naturalization Records; National Archives, History of the Certificate of Citizenship; USCIS, Immigration and Nationality Act.

The modern system therefore reflects two histories at once: Congress’s continuing power to establish a uniform rule, and successive changes to who may qualify and which institution decides an application. Historical restrictions should not be confused with the eligibility rules in force today.

The Current Statutory Framework

The principal naturalization provisions appear in INA §§ 310–347, codified at 8 U.S.C. §§ 1421–1458. Several sections are especially important:

  • 8 U.S.C. § 1421: Authority to naturalize and judicial review of certain denials

  • 8 U.S.C. § 1423: English-language and civics requirements, with statutory exceptions

  • 8 U.S.C. § 1427: General residence, physical-presence, and good-moral-character requirements

  • 8 U.S.C. § 1429: Lawful admission for permanent residence and restrictions involving removal proceedings

  • 8 U.S.C. § 1430: Certain naturalization provisions for spouses of U.S. citizens

  • 8 U.S.C. §§ 1445–1448: Application, examination, decision, and Oath of Allegiance

Implementing Naturalization Regulations

The statutes establish the requirements for naturalization. The implementing regulations in Title 8, Chapter I, Subchapter C of the Code of Federal Regulations explain how USCIS applies those requirements and processes applications. The links below provide the full regulatory text, rather than excerpts; readers can also browse the complete set of nationality regulations.

Two additional sets of regulations matter when a different route to citizenship applies: 8 C.F.R. Parts 328–329, concerning naturalization based on qualifying military service, and 8 C.F.R. Part 322, concerning applications for certain children born outside the United States. A person who may already have acquired citizenship automatically through a parent should evaluate that claim before filing a naturalization application.

The eCFR is updated as regulations change. For a filing or legal analysis, consult the version in effect on the relevant date and read the applicable statute alongside the regulation. eCFR, Title 8 nationality regulations.

Basic Requirements for Naturalization

Under the general five-year route, an applicant ordinarily must:

  1. Be at least 18;

  2. Have been lawfully admitted for permanent residence;

  3. Maintain the required continuous residence;

  4. Be physically present in the United States for at least 30 months of the relevant five-year period;

  5. Meet the applicable state or USCIS district residence requirement; and

  6. Establish good moral character, attachment to the Constitution, and the required knowledge of English and U.S. civics, subject to applicable exceptions.

These requirements involve more than holding a green card for five calendar years: extended trips abroad, for example, can affect continuous residence even when the applicant has accumulated enough days of physical presence. 8 U.S.C. §§ 1423, 1427, 1429; USCIS Policy Manual, Continuous Residence; USCIS Policy Manual, Physical Presence.

Some applicants qualify under a different statutory route. An eligible permanent resident married to and living in marital union with a U.S. citizen may generally apply under a three-year framework, subject to its own requirements. Other provisions address certain military service and particular circumstances involving U.S. citizens working abroad. The applicable route should be identified before calculating an applicant’s filing date. 8 U.S.C. §§ 1430, 1439–1440; USCIS Policy Manual, Volume 12.

General Overview of the Naturalization Process

  1. Determine whether citizenship is already held. Review the applicant’s place of birth, parents’ citizenship and residence histories, and any potential automatic acquisition of citizenship after birth. A person who is already a citizen should assess the appropriate way to obtain proof of that status. USCIS Policy Manual, Volume 12.

  2. Identify the correct naturalization route and filing date. Confirm lawful permanent residence and examine travel, residence, marital history where relevant, and any statutory exception. USCIS permits filing up to 90 days before completing certain continuous-residence periods, but that early-filing rule does not waive other eligibility requirements. USCIS Policy Manual, Jurisdiction, Place of Residence, and Early Filing.

  3. File Form N-400. The applicant submits the current Application for Naturalization with the required evidence and fee or an available fee request. USCIS may schedule biometrics and conduct background and eligibility checks. Check form instructions and fees when filing because they can change. USCIS Form N-400.

  4. Attend the interview and examination. A USCIS officer reviews the application, verifies eligibility, and administers the applicable English and civics examinations unless an exception or accommodation applies. USCIS has changed its civics-test materials over time, so applicants should use the version applicable to their filing. USCIS, Naturalization Interview and Test; USCIS, 2025 Civics Test.

  5. Receive a decision and, if approved, take the oath. Approval is ordinarily followed by a naturalization ceremony. For most applicants, citizenship begins when they take the Oath of Allegiance, and the Certificate of Naturalization then serves as evidence of it. A denial may be subject to administrative review and, after the required steps, judicial review. 8 U.S.C. §§ 1421(c), 1447–1448; USCIS Policy Manual, Volume 12.

Why the distinction matters

A naturalization application asks the government to confer citizenship under a statute. A citizenship claim based on birth or automatic acquisition through a parent asks the government to recognize and document citizenship that arose by operation of law. A “derivative” citizen, i.e., one who obtained citizenship automatically through their parents, will ask USCIS to recognize his or her citizenship through a different process—generally by filing USCIS Form N600. The distinction between the processes affects which facts must be proved, which application or document is appropriate, and when citizenship began. It is the first issue to resolve in any individual citizenship analysis. U.S. Constitution, Fourteenth Amendment; 8 U.S.C. §§ 1431, 1433.

Frequently Asked Questions About Naturalization

1. What is naturalization?

Naturalization is the process through which a person who was not a U.S. citizen at birth becomes one under federal law. Most applicants must first become lawful permanent residents, meet the applicable eligibility requirements, file Form N-400, and take the Oath of Allegiance after approval. 8 U.S.C. §§ 1421–1448.

2. Could I already be a U.S. citizen without applying for naturalization?

Yes. Some people acquire citizenship at birth through a U.S. citizen parent or automatically become citizens after birth when statutory conditions are met. If you may already be a citizen, determine whether you need proof of citizenship before filing Form N-400. USCIS, I Am the Child of a U.S. Citizen.

3. What is the difference between Form N-400 and Form N-600?

Form N-400 is an application to become a citizen through naturalization. Form N-600 generally seeks a Certificate of Citizenship to document citizenship a person already acquired at birth or automatically through a parent after birth. The correct form depends on when and how citizenship arose. USCIS, Form N-400; USCIS, Form N-600.

4. Do I have to hold a green card for five years before applying?

Five years of lawful permanent residence is the general route, but it is not the only route. Certain spouses of U.S. citizens may qualify under a three-year framework, and other provisions address qualifying military service and special circumstances. Residence time alone does not establish eligibility; travel and the other statutory requirements must also be reviewed. 8 U.S.C. §§ 1427, 1430.

5. Can I file Form N-400 before my five-year or three-year anniversary?

USCIS generally permits an eligible applicant to file up to 90 days before completing the applicable continuous-residence period. That early-filing rule does not waive requirements that must be satisfied by the filing date or at a later stage of the case. Calculate the date under the route that actually applies to you. USCIS Policy Manual, Early Filing.

6. What is the difference between continuous residence and physical presence?

Continuous residence concerns whether the United States remained your residence during the required period. Physical presence counts the time you were actually in the United States. A long trip abroad can disrupt continuous residence even when you have accumulated enough days of physical presence. USCIS Policy Manual, Continuous Residence; USCIS Policy Manual, Physical Presence.

7. Will travel outside the United States prevent me from naturalizing?

Travel does not automatically prevent naturalization, but the dates and length of each trip matter. An extended absence can raise a continuous-residence issue, and time spent abroad does not count toward physical presence. Reconstruct your travel history before choosing a filing date. 8 C.F.R. Part 316.

8. Do I have to pass English and civics tests?

Most applicants must demonstrate the required English ability and knowledge of U.S. history and government during the naturalization examination. Statutory exceptions, disability exceptions, and accommodations may apply, and USCIS has different civics-test materials depending on when an application was filed. Review the rules that apply to your application before studying. 8 C.F.R. Part 312; USCIS, 2025 Civics Test.

9. What if I cannot take the tests because of a disability?

A qualifying medically determinable impairment may support an exception from the English and/or civics requirements. The exception ordinarily requires Form N-648, completed by an authorized medical professional; a diagnosis alone does not automatically excuse testing. USCIS also provides accommodations that are distinct from a testing exception. USCIS, Exceptions and Accommodations; USCIS, Form N-648.

10. Does an arrest or conviction mean I cannot become a citizen?

It depends on the conduct, the precise disposition, and the applicable law. Some conduct can bar naturalization, while other matters require a careful good-moral-character or immigration-status analysis even if the charges were dismissed or the record was expunged. Obtain the complete court records and review the issue before filing. USCIS Policy Manual, Good Moral Character.

11. What happens after I submit Form N-400?

USCIS issues a receipt notice, conducts required checks, and may schedule a biometrics appointment. It then schedules an interview at which an officer reviews the application and administers any required tests. USCIS may approve the application, request more information, continue the examination, or deny it. USCIS, 10 Steps to Naturalization; 8 C.F.R. Part 335.

12. Am I a citizen as soon as USCIS approves my application?

Generally, no. An applicant ordinarily becomes a citizen upon taking the Oath of Allegiance at a naturalization ceremony, not merely when USCIS approves Form N-400. After the oath, the new citizen receives a Certificate of Naturalization and should review it for errors. USCIS, Naturalization: What to Expect; 8 C.F.R. Parts 337–338.

13. What can I do if USCIS denies my naturalization application?

An applicant can generally request an administrative hearing to review the denial. After the required administrative review, federal district court review may be available. The deadline and appropriate response depend on the denial notice, so review it promptly. 8 U.S.C. § 1421(c); 8 C.F.R. Part 336.

14. Can Charles International Law help me prepare my application?

Yes. We can assess whether you need to naturalize or may already be a citizen, determine the applicable eligibility route, review travel and other potential issues, prepare Form N-400 with you, and help you prepare for the USCIS interview within the scope of an engagement. To discuss your circumstances, schedule an immigration consultation and select “Naturalization / Citizenship” as the reason for your appointment.

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