How Can a Foreigner Become a U.S. Citizen: Paths, Tests, and Oath

A foreigner can become a U.S. citizen by first obtaining a green card, living in the country for the required number of years, passing English and civics tests, showing good moral character, and taking the Oath of Allegiance. That is the naturalization process, and it is the only route for adults who were not born U.S. citizens or acquire citizenship automatically through a parent. Most applicants follow a five-year path, but spouses of U.S. citizens qualify in three years and some military service members qualify sooner still. The application fee is $710 online or $760 by mail, and the median time from filing to decision is roughly 6.4 months in fiscal year 2026.

The Baseline You Have to Meet

Three requirements come before everything else. You must be at least 18 years old, you must already be a lawful permanent resident, and you must have held that status continuously for the years your path requires.¹ There is no shortcut that skips the green card, with narrow exceptions for certain military personnel serving during designated periods of hostility.

Getting the green card is a separate immigration process handled before naturalization ever enters the picture. Only once you hold permanent residency does the naturalization clock start running.

The Three Paths and How Long Each Takes

Standard Five-Year Path

The most common route requires five years of continuous residence as a green card holder immediately before filing.² Within those five years you must also have been physically present in the United States for at least 30 months total.³

Continuous residence and physical presence are not the same test. Continuous residence means keeping the U.S. as your primary home. Physical presence is the raw count of days you were actually in the country. You need to satisfy both.

You can file up to 90 days before you hit the five-year mark, which trims the total timeline.⁴ Approval still waits until you reach the full five years.

Three-Year Path for Spouses of U.S. Citizens

Marriage to a U.S. citizen cuts the continuous residence requirement to three years. You must have been living in marital union with your citizen spouse throughout that three-year period, and your spouse must have been a citizen the whole time.⁵ Physical presence drops to 18 months out of the three years.⁶ Divorce or legal separation before approval pushes you back to the standard five-year path.

Military Service

Noncitizens who serve honorably in the U.S. Armed Forces for at least one year may apply for naturalization without meeting the usual residence or physical presence requirements, provided they file while still serving or within six months of an honorable discharge.⁷ For service members on active duty during designated periods of hostility, the residence and physical presence requirements can be waived entirely.⁸

How Time Abroad Can Break Your Clock

Long trips outside the United States are one of the most common ways applicants sabotage their own timeline without knowing it. Travel falls into three tiers:

Under six months: generally no problem. USCIS treats these as routine travel.
Six to twelve months: a single trip of this length creates a presumption that your continuous residence was broken. You can rebut it with evidence that you kept your job, your family stayed in the U.S., you maintained your home, and you did not take employment abroad, but the burden is on you.⁹
Twelve months or more: continuous residence is automatically broken. You must wait four years and one day from your return before filing on the five-year path, or two years and one day on the three-year spousal path.⁹

If a job requires long stints overseas, filing Form N-470 before leaving may preserve continuous residence, but only for specific categories of employment such as certain government and corporate positions.

The English and Civics Tests

At the naturalization interview, a USCIS officer tests your ability to read, write, and speak basic English. The speaking portion happens naturally as the officer walks through your application. You will also read one sentence aloud and write one down.¹⁰

The civics test is oral. For applications filed on or after October 20, 2025, the officer asks up to 20 questions drawn from a bank of 128 on U.S. history and government. You need 12 correct to pass; the officer stops once you reach 12 right or 9 wrong.¹¹ USCIS publishes free study materials. Fail either test and you get one retake at a later appointment.

Who Is Exempt From the English Test

Two age-based rules waive the English requirement:

50/20 rule: you are at least 50 and have been a permanent resident for at least 20 years.
55/15 rule: you are at least 55 and have been a permanent resident for at least 15 years.¹⁰

Under either rule, you still take the civics test but may do so in your native language with an interpreter.¹² Applicants who are 65 or older with at least 20 years as a permanent resident get a shorter civics test drawn from a smaller pool of 20 questions.

Applicants whose physical, developmental, or mental condition prevents them from meeting the requirements can request a waiver by filing Form N-648 with a certification from a licensed medical doctor, osteopathic physician, or clinical psychologist.¹³

Good Moral Character

You must show good moral character throughout the statutory period before your application and continuing through the oath.¹⁴ That period is five years for the standard path or three years for the marriage-based path. USCIS also has discretion to consider conduct before the statutory period when relevant.

Serious criminal convictions, drug offenses, fraud, and extended jail sentences all raise red flags. So do failing to pay taxes, lying on government forms, and neglecting court-ordered child support.¹⁵

Selective Service Registration for Men

Male applicants ages 18 to 25 living in the United States must register with the Selective Service System. Knowingly failing to register during that window can result in a denial for lack of good moral character and failure to show attachment to the Constitution.¹⁶

If you are under 26, you are generally ineligible until you register. Between 26 and 31, USCIS will let you try to show your failure to register was not knowing or willful. After 31, the failure typically falls outside the statutory period and no longer blocks the application.¹⁶ If you are not sure whether you registered, request a status information letter from the Selective Service System before filing.

Filing Form N-400

The application is Form N-400. You can file online through the USCIS portal or mail a paper form to a USCIS lockbox. Online filing costs $710; paper filing is $760.¹⁷ A reduced $380 fee is available at household incomes between 150% and 200% of the federal poverty guidelines, and applicants below 150% can request a full waiver on Form I-912.¹⁸

The form asks for detailed personal history over the five years (or three, for the marriage path) before filing: every address, every employer, every trip abroad with exact dates, marital history, children, organizational memberships, and any contact with law enforcement or immigration authorities. Gather the records before you start.

Accuracy is not optional. Providing false information on the N-400 is a federal crime carrying fines and up to 10 years in prison, with penalties reaching 25 years if the fraud is connected to terrorism.¹⁹ Honest mistakes are different from intentional fraud, but even accidental errors can trigger delays and requests for more evidence.

Include a photocopy of both sides of your green card. Marriage-based applicants also send a marriage certificate and proof any prior marriages ended.²⁰ Bring tax returns or IRS transcripts for the statutory period as well, since USCIS may ask for them.

After You File: Biometrics, Interview, Oath

Once USCIS accepts your application, you may be scheduled for a biometrics appointment at a local Application Support Center, where your fingerprints, photograph, and signature are collected for an FBI background check.²¹ USCIS sometimes reuses recent biometrics from a prior filing.

After the background check clears, USCIS schedules the naturalization interview. An officer reviews your entire application, asks you to confirm or update your answers, and administers the English and civics tests. Bring your appointment notice, your green card, a state-issued photo ID, and every passport (current and expired) covering your time as a permanent resident.²¹

The officer can approve on the spot, continue the case for more documentation, or deny it. Approved applicants take the Oath of Allegiance at a naturalization ceremony, pledging support to the Constitution and renouncing allegiance to any foreign government.²² Some field offices swear you in the same day; others schedule the ceremony for later. You receive a Certificate of Naturalization at the ceremony, and at that moment you are a U.S. citizen.

If Your Application Is Denied

A denial has two possible responses: appeal or reapply.

To appeal, file Form N-336 within 30 calendar days of the denial notice (33 days if mailed). A different USCIS officer reviews the case fresh.²³ The fee is $830 by paper or $780 online. Miss the 30-day window and USCIS will generally reject the request and keep the fee.

Reapplying with a new N-400 is often the better option when the problem is something fixable, like failing the civics test or not yet meeting physical presence. A new application means paying the full fee again, but a prior denial does not reset your eligibility clocks; qualifying time keeps accumulating.

Children of Naturalized Parents

When a parent naturalizes, minor children may become U.S. citizens automatically, without a separate application. Four conditions must all be true before the child turns 18:

At least one parent is a U.S. citizen (by birth or naturalization).
The child is under 18.
The child is a lawful permanent resident.
The child lives in the United States in the legal and physical custody of the U.S. citizen parent.²⁴

When all four align, citizenship is automatic. No ceremony, no oath. But the child does not receive documentation on their own. To get proof, file Form N-600, Application for Certificate of Citizenship.²⁵ The certificate is the cleanest proof of status for school, work, and passport applications later.

After You Take the Oath

The United States does not prohibit dual citizenship. Federal law does not require you to formally give up your other nationality, and naturalizing here does not automatically revoke citizenship in your home country, though some countries revoke it on their end.²⁶ Dual citizens owe allegiance to both countries and must obey the laws of each.

Update your record with the Social Security Administration by requesting a replacement card that reflects your new citizenship status. You can start online, then bring proof of identity and status to an appointment. The card arrives in about 5 to 10 business days.²⁷

Apply for a U.S. passport. First-time applicants must apply in person at an acceptance facility, usually a post office or county clerk’s office. The application fee is $130 plus a $35 execution fee, for a total of $165 for a standard adult passport book.²⁸ Dual nationals must use the U.S. passport when entering and leaving the United States, even if they also hold a foreign one.

1
U.S. Citizenship and Immigration Services. I Am a Lawful Permanent Resident of 5 Years
2
Office of the Law Revision Counsel. 8 USC 1427 – Requirements of Naturalization
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eCFR. 8 CFR 316.2 – Eligibility
4
U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 12 Part D Chapter 6 – Jurisdiction, Place of Residence, and Early Filing
5
Office of the Law Revision Counsel. 8 USC 1430 – Married Persons and Employees of Certain Nonprofit Organizations
6
U.S. Citizenship and Immigration Services. Chapter 3 – Spouses of U.S. Citizens Residing in the United States
7
Office of the Law Revision Counsel. 8 USC 1439 – Naturalization Through Service in the Armed Forces
8
U.S. Citizenship and Immigration Services. Chapter 3 – Military Service During Hostilities (INA 329)
9
eCFR. 8 CFR 316.5 – Residence in the United States
10
Office of the Law Revision Counsel. 8 USC 1423 – Requirements as to Understanding the English Language, History, Principles and Form of Government of the United States
11
U.S. Citizenship and Immigration Services. Study for the Test
12
U.S. Citizenship and Immigration Services. Chapter 2 – English and Civics Testing
13
U.S. Citizenship and Immigration Services. N-648, Medical Certification for Disability Exceptions
14
U.S. Citizenship and Immigration Services. Chapter 9 – Good Moral Character
15
eCFR. 8 CFR 316.10 – Good Moral Character
16
U.S. Citizenship and Immigration Services. Chapter 7 – Attachment to the Constitution
17
U.S. Citizenship and Immigration Services. N-400, Application for Naturalization
18
U.S. Citizenship and Immigration Services. I-912, Request for Fee Waiver
19
Office of the Law Revision Counsel. 18 USC 1425 – Procurement of Citizenship or Naturalization Unlawfully
20
U.S. Citizenship and Immigration Services. Document Checklist
21
U.S. Citizenship and Immigration Services. Naturalization: What to Expect
22
Office of the Law Revision Counsel. 8 USC 1448 – Oath of Renunciation and Allegiance
23
U.S. Citizenship and Immigration Services. Request for a Hearing on a Decision in Naturalization Proceedings
24
U.S. Citizenship and Immigration Services. Automatic Acquisition of Citizenship After Birth (INA 320)
25
U.S. Citizenship and Immigration Services. N-600, Application for Certificate of Citizenship Frequently Asked Questions
26
U.S. Department of State. Dual Nationality
27
Social Security Administration. Update Citizenship or Immigration Status
28
U.S. Department of State. United States Passport Fees for Acceptance Facilities