Ways to Become a U.S. Citizen: Birth, Naturalization, Military Service

There are four ways to become a U.S. citizen: being born on U.S. soil, being born abroad to a U.S. citizen parent, naturalizing as a lawful permanent resident, or naturalizing through military service. Each has its own eligibility rules and timeline. Naturalization is the route most adult immigrants take, and it generally requires five years as a green card holder before you can even apply. Once you file, the median time from application to oath is about 6.4 months.

Born on U.S. Soil

Almost anyone born in the United States is a citizen at birth, regardless of their parents’ immigration status. The rule comes from the Fourteenth Amendment, which grants citizenship to anyone born in the country and subject to its jurisdiction.¹ It applies in all fifty states, the District of Columbia, and the major territories: Puerto Rico, Guam, the U.S. Virgin Islands, and the Commonwealth of the Northern Mariana Islands.²

Nothing has to be filed. Citizenship exists by operation of law from the moment of birth, and a birth certificate from any of those jurisdictions is proof. The State Department accepts either a birth certificate or a U.S. passport as evidence when issuing travel documents.³

Born Abroad to a U.S. Citizen Parent

A child born outside the United States can still be a citizen from birth if at least one parent is a U.S. citizen who meets the physical presence rule. When one parent is a citizen and the other is not, the citizen parent must have lived in the United States for at least five years before the child’s birth, with at least two of those years after age fourteen.⁴ Time on active military duty or in U.S. government work abroad counts. When both parents are citizens, the rules are less demanding.

A separate route covers children already born abroad who later move to the United States. Under the Child Citizenship Act of 2000, a child automatically becomes a citizen once all four of these are true: at least one parent is a U.S. citizen, the child is under eighteen, the child holds a green card, and the child lives in the United States in the citizen parent’s legal and physical custody.⁵ The status takes effect automatically. Filing Form N-600 with USCIS gets you a Certificate of Citizenship as formal proof.⁶

Naturalization as a Lawful Permanent Resident

Naturalization is the standard path for adult immigrants. You file Form N-400 with USCIS, complete biometrics, sit for an interview and tests, and take the Oath of Allegiance.⁷ Before you file, you need to meet every baseline requirement.

Basic Eligibility

You are at least eighteen when you file.
You have held a green card for at least five years, or three years if you are married to a U.S. citizen and have lived in marital union with that spouse the entire three-year period.
You have lived continuously in the United States during that five- or three-year period.
You have been physically present in the United States for at least thirty months out of the past five years, or eighteen months out of three years for those married to a citizen.
You have lived in the state or USCIS district where you file for at least three months.

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Continuous Residence and Travel

Continuous residence trips up frequent travelers more than any other rule. A trip of six months or less is fine. An absence of more than 180 days but less than a year creates a legal presumption that continuous residence has been broken. You can overcome that presumption by showing you kept your job, home, and immediate family in the United States, but the burden is on you. An absence of a full year or more automatically breaks continuous residence, and you would need to restart the clock unless you had prior approval through Form N-470, which preserves residence for certain employees working abroad for the U.S. government, qualifying employers, or religious organizations.⁹

Good Moral Character

USCIS reviews your conduct throughout the statutory period, five years for most applicants and three years for those married to a citizen. Officers look at criminal records, tax filings, and overall conduct. A conviction for murder or an aggravated felony is a permanent bar. Conditional bars during the statutory period include crimes involving dishonesty or violence, controlled substance violations beyond simple possession of a small amount of marijuana, incarceration totaling 180 days or more, and making false statements under oath to obtain an immigration benefit.¹⁰

Other issues matter too. Willful failure to support dependents, two or more DUI convictions during the statutory period, and failing to file tax returns all raise red flags. USCIS weighs negative conduct against positive contributions like tax compliance and community involvement.¹¹

Male applicants who lived in the United States between ages eighteen and twenty-six have an extra requirement: Selective Service registration. If you were required to register and didn’t, USCIS may treat that as evidence of poor moral character. Applicants between twenty-six and thirty-one who never registered can request a status information letter from the Selective Service System explaining whether the failure was knowing and willful. Applicants over thirty-one are generally unaffected because the omission falls outside the statutory review period.¹²

Filing, Fees, and Timeline

You can file Form N-400 online through your USCIS account or by mail. The fee is $710 online and $760 on paper.¹³ A reduced fee is available through Form I-942 if your household income falls between 150% and 200% of federal poverty guidelines,¹⁴ and a full fee waiver through Form I-912 for applicants receiving means-tested benefits or with very low income.¹⁵

Preparation matters. Gather your federal tax returns for the past five years, a complete list of every trip outside the country with dates, your green card, and documentation of any arrests, citations, or name changes. Discrepancies between your application and government records lead to delays or requests for additional evidence, so cross-reference your travel history against your passport stamps before submitting anything.

After filing, USCIS schedules a biometrics appointment at a local Application Support Center for fingerprints, a photograph, and your signature.¹⁶ From filing to completion, median processing time is roughly 6.4 months, though individual cases vary.

Interview, English Test, and Civics Test

Every applicant sits for an in-person interview with a USCIS officer, who reviews your application under oath and asks about your background. The English and civics testing happens at that interview.

English has three parts. Speaking is assessed through the interview conversation itself. For reading, you must correctly read aloud one of three sentences. For writing, you must correctly write one of three dictated sentences.¹⁷

The civics test changed for applications filed on or after October 20, 2025. The officer now asks up to twenty questions drawn from a bank of 128 covering American history and government. You need at least twelve correct to pass, and the officer stops once you have twelve right or nine wrong.¹⁸ The full question bank and free study materials are on the USCIS website. If you fail either test, you get one chance to retake the failed portion within sixty to ninety days.

Test Exemptions

Two age-based rules excuse you from the English requirement entirely:

The 50/20 rule: you are at least fifty at filing and have held a green card for at least twenty years.
The 55/15 rule: you are at least fifty-five and have held a green card for at least fifteen years.

If either rule applies, you still take the civics test, but you can take it in your native language through an interpreter you provide. Applicants who are sixty-five or older with at least twenty years as a permanent resident get further accommodation on the civics portion, including a shorter list of study questions.¹⁹

A medical disability exception can waive both English and civics entirely. A licensed physician or clinical psychologist must complete Form N-648 certifying that a physical or mental condition prevents you from learning or demonstrating the material, and the condition must have lasted or be expected to last at least twelve months. Advanced age or general illiteracy on their own do not qualify.¹⁹

The Oath and Dual Citizenship

The last step is the oath ceremony, conducted either administratively by USCIS or judicially by a federal or state court.²⁰ The Oath of Allegiance includes language about renouncing allegiance to foreign states, which worries many applicants, but U.S. law does not actually require you to give up a foreign nationality. The State Department states that citizens may hold multiple nationalities without risk to their U.S. citizenship.²¹ Whether your other country recognizes dual nationality is a separate question governed by its own laws. After the ceremony you receive a Certificate of Naturalization, which is your primary proof of citizenship until you obtain a passport.

Naturalization Through Military Service

Members of the U.S. Armed Forces have a faster route that waives several civilian requirements. The rules split by whether service falls in peacetime or during a designated period of hostility. Median processing for military naturalization runs about 3.2 months, roughly half the civilian timeline.

Peacetime Service

If you have served honorably for at least one year in aggregate, you can naturalize without meeting the five-year residence or physical presence requirements. You must file while still serving or within six months of an honorable separation.²² All other requirements, including good moral character, English, and civics, still apply.

Service During Hostilities

Service during a designated period of hostility drops even more barriers. There is no minimum service duration, and the residence and physical presence requirements are waived entirely. You do not need to be a permanent resident to qualify.²³

Both military paths require Form N-426 (Request for Certification of Military or Naval Service), signed by authorized personnel in your branch to verify your service record.²⁴ One catch: citizenship obtained through military service can be revoked if you are separated under other than honorable conditions before completing five years of honorable service.²³

Military Family Members

Spouses of service members stationed abroad may also qualify for expedited naturalization. If your U.S. citizen spouse is in the military and will be stationed overseas for at least a year, you can naturalize without the standard residence and physical presence requirements, provided you are a permanent resident, pass the interview and tests, and intend to reside abroad with your spouse and return when orders end. In some cases the process can be completed overseas without returning to the United States.²⁵

If Your Application Is Denied

A denial does not have to be the end of the road. You have thirty calendar days from receiving the denial notice, or thirty-three days if it was mailed, to file Form N-336 requesting a hearing before a different USCIS officer, who reviews the case from scratch.²⁶ If the denial was based on failing the English or civics test, reapplying with a new Form N-400 after additional study is often the better move.

1
Constitution Annotated. Amdt14.S1.1.1 Historical Background on Citizenship Clause
2
U.S. Citizenship and Immigration Services. USCIS Policy Manual – Becoming a U.S. Citizen
3
U.S. Department of State. Get Citizenship Evidence for a U.S. Passport
4
Office of the Law Revision Counsel. 8 USC 1401 – Nationals and Citizens of United States at Birth
5
Office of the Law Revision Counsel. 8 USC 1431 – Children Born Outside the United States; Conditions Under Which Citizenship Automatically Acquired
6
U.S. Citizenship and Immigration Services. Instructions for Application for Certificate of Citizenship
7
U.S. Citizenship and Immigration Services. N-400, Application for Naturalization
8
U.S. Citizenship and Immigration Services. I am a Lawful Permanent Resident of 5 Years
9
U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 12 Part D Chapter 3 – Continuous Residence
10
U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 12 Part F Chapter 5 – Conditional Bars for Acts in Statutory Period
11
U.S. Citizenship and Immigration Services. Policy Memorandum – Restoring a Rigorous, Holistic, and Comprehensive Good Moral Character Evaluation Standard
12
Selective Service System. Applicants Over 31 Years of Age – USCIS Policy
13
U.S. Citizenship and Immigration Services. Form N-400 Application for Naturalization Filing Fees
14
U.S. Citizenship and Immigration Services. I-942, Request for Reduced Fee
15
U.S. Citizenship and Immigration Services. I-912, Request for Fee Waiver
16
U.S. Citizenship and Immigration Services. Preparing for Your Biometric Services Appointment
17
U.S. Citizenship and Immigration Services. The Naturalization Interview and Test
18
U.S. Citizenship and Immigration Services. Study for the Test
19
U.S. Citizenship and Immigration Services. Exceptions and Accommodations
20
U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 12 Part J Chapter 6 – Judicial and Expedited Oath Ceremonies
21
U.S. Department of State. Dual Nationality
22
Office of the Law Revision Counsel. 8 USC 1439 – Naturalization Through Active-Duty Service in the Armed Forces During Peacetime
23
Office of the Law Revision Counsel. 8 USC 1440 – Naturalization Through Active-Duty Service During Hostilities
24
U.S. Citizenship and Immigration Services. N-426, Request for Certification of Military or Naval Service
25
U.S. Citizenship and Immigration Services. Citizenship for Military Family Members
26
U.S. Citizenship and Immigration Services. Request for a Hearing on a Decision in Naturalization Proceedings