The N-400 is the official application for U.S. naturalization—the process by which a lawful permanent resident becomes a U.S. citizen. If you want to naturalize, the N-400 is the form you file with U.S. Citizenship and Immigration Services (USCIS). It's one of the most consequential documents in the immigration system, and understanding it fully is the first step toward a successful citizenship application.
This guide explains what the N-400 form is, who's eligible to file it, what it asks, how much it costs, and how the process unfolds from application to oath ceremony.
Form N-400 is filed by lawful permanent residents (green card holders) who want to apply for U.S. citizenship through naturalization. You don't file the N-400 if you became a citizen automatically at birth (by being born to a U.S. citizen parent) or if you acquired citizenship through a parent's naturalization while you were a minor. For those situations, different forms apply (like the N-600 for a Certificate of Citizenship).
The N-400 is specifically for naturalization—voluntarily applying to become a citizen after meeting the required conditions as a permanent resident. Most applicants are either:
Permanent residents who have held their green card for at least five years and meet the physical presence and good moral character requirements. Or permanent residents who are married to and living with a U.S. citizen and have held their green card for at least three years (the three-year rule).
There are other eligibility categories—military service members and veterans have different rules, as do certain special immigrant categories—but five years and three years (for spouses of citizens) are the most common pathways.
The N-400 is a comprehensive application that covers your personal and legal history extensively. The form has multiple parts:
Personal information: Your full legal name, any other names you've used, date of birth, nationality, physical description, contact information, and Social Security number.
Residence history: Your addresses for the past five years (or three years if applying under the spouse-of-citizen rule). USCIS verifies this against the address history on your immigration file.
Employment history: Your employers for the past five years. This section helps USCIS verify physical presence and continuity of residence.
Time outside the U.S.: Every trip outside the United States of 24 hours or more during the past five years, including destination, dates, and purpose. Continuous residence and physical presence requirements have specific technical definitions—this section is critical to verify them.
Marital history: Whether you're married, your spouse's name and immigration status, and any prior marriages. If you're applying under the three-year spouse rule, the status of your current marriage is especially important.
Children: A complete list of all your children, their citizenship status, and residence.
Good moral character questions: This is one of the most detailed and legally significant parts of the form. USCIS asks about criminal history (including arrests, citations, and convictions even for offenses you think were expunged), involvement in criminal organizations, alcohol and drug-related issues, lying to immigration authorities, failing to pay taxes or court-ordered support, and several other categories. You must answer these questions honestly—misrepresentation on an immigration application is a federal offense with serious consequences.
Selective Service: Male applicants who were permanent residents between ages 18 and 26 must have registered with the Selective Service. The N-400 asks whether you registered and, if not, requires an explanation.
Attachment to the Constitution: Questions about whether you support the Constitution, whether you're willing to bear arms or perform non-combatant service for the U.S., and whether you're willing to take the Oath of Allegiance.
Before filing, you need to confirm you actually qualify. Key requirements:
Age: You must be 18 or older to file. (Children can sometimes acquire citizenship through a parent's naturalization without filing N-400, but they need to meet specific requirements.)
Permanent resident status: You must have a valid green card and maintain it throughout the application process. If your green card expires or is revoked during processing, your application may be affected.
Continuous residence: You must have continuously resided in the U.S. as a permanent resident for the required period—five years for most applicants, three years for spouses of U.S. citizens. Extended absences (typically over six months in a single trip) can break continuous residence, potentially resetting your clock.
Physical presence: You must have been physically present in the U.S. for at least half the required continuous residence period—30 months out of 60, or 18 months out of 36. Every day outside the U.S. counts against this.
State of residence: You must have lived in the state or USCIS district where you're filing for at least three months before filing.
Good moral character: You must demonstrate good moral character during the required statutory period. Certain criminal convictions permanently bar naturalization; others bar it for a period of time. Lying on immigration applications, failing to file taxes, and certain other conduct also affect this determination.
English and civics: Most applicants must demonstrate ability to read, write, and speak English (with some exceptions for older applicants with long-term permanent residence) and pass a civics test covering U.S. history and government. The civics test has 100 potential questions, and the officer asks you up to 10 at your interview. You need to answer at least 6 correctly.
As of 2024, the N-400 filing fee is $760 for most applicants. If you're applying online, there's an $85 biometrics fee on top of that for most applicants, though fee structures change—check the USCIS website for current fees before filing. Fee waivers are available for applicants who demonstrate financial hardship.
Military applicants and certain other categories may be exempt from fees. Check Form I-912 (Request for Fee Waiver) if you believe you qualify for a waiver.
The process after filing:
Biometrics appointment: USCIS will schedule you for a biometrics appointment where they take your fingerprints, photo, and signature for a background check. You'll receive a notice with the appointment location and time—attend it and bring your appointment notice and photo ID.
Interview scheduling: After your biometrics and background check, USCIS schedules your naturalization interview at the local field office. Wait times for interviews vary significantly by field office and time of year—anywhere from a few months to over a year in heavily loaded offices.
Naturalization interview: The interview is conducted by a USCIS officer. You'll be placed under oath, the officer will review your N-400 with you, ask questions about your application and good moral character, administer the English and civics tests (unless you're exempt), and make a determination. The officer may approve your application at the interview, continue it for additional review, or deny it.
Oath ceremony: If approved, you'll be scheduled for an oath ceremony—either at the USCIS field office or at a court location. You take the Oath of Allegiance, and you become a U.S. citizen at that moment. You'll receive your Certificate of Naturalization at the ceremony.
The N-400 is detailed, and mistakes cause delays or denials. Common issues:
Incomplete answers: Every question on the form requires an answer. Leaving sections blank or writing "N/A" where a real answer is expected causes processing delays. Read each question carefully and answer it fully.
Underreporting travel: USCIS checks your travel history through Customs and Border Protection records. If your reported trips don't match CBP records, it raises questions. Include every trip over 24 hours, even trips you took years ago that you think were insignificant.
Failing to disclose criminal history: The N-400 asks about arrests and criminal charges, not just convictions. Even if charges were dropped, dismissed, or expunged, you need to disclose them and explain. Failure to disclose is considered misrepresentation, which is itself a disqualifying factor.
Filing too early: USCIS accepts N-400 applications up to 90 days before you reach the required continuous residence threshold. Filing earlier than 90 days before your eligibility date results in rejection. Calculate your eligibility date carefully and don't file before the 90-day window opens.
Using outdated forms: Always download the current version of Form N-400 directly from USCIS.gov. Outdated versions are rejected. The current version number appears at the bottom of each page.
Processing times vary dramatically by USCIS field office and current caseload. Historically, processing has ranged from 8 months to over 2 years at different offices and periods. You can check current processing times by office on the USCIS website. File online when possible—online applications are generally processed faster than paper applications and allow you to track your case status more easily.
If your case is significantly outside the published processing time for your office, you can make an inquiry through your USCIS online account or contact the USCIS Contact Center. Congressional representative offices can also sometimes assist with expediting or inquiring about long-delayed cases.
The civics test is one of the parts of naturalization applicants worry about most, but it's very manageable with focused preparation. USCIS publishes all 100 possible civics test questions—along with the acceptable answers—on its website. The officer will ask you up to 10 questions chosen from that list, and you need to answer at least 6 correctly.
The questions cover topics like U.S. history (American Revolution, Civil War, founding documents), U.S. government structure (branches of government, how bills become laws), rights and responsibilities, and geography. Most applicants find the material straightforward once they've reviewed it—the challenge is memorizing specific answers that match USCIS's accepted response list, not just general knowledge of the topic.
Study the official USCIS study materials, not third-party summaries that may use different phrasing. The officer needs to hear answers that match the accepted response list. Practice with someone who can quiz you orally—the test is verbal, not written, and saying answers aloud is different from recognizing them on a page.
If you're 65 or older and have been a permanent resident for 20 or more years, you only need to answer 6 of 10 questions from a special shorter list of 20 questions. Confirm your eligibility for this accommodation with USCIS if it applies to you.
The N-400 process is thorough by design—U.S. citizenship is a permanent status with significant rights and obligations attached to it. Prepare carefully, be honest throughout, and understand that the process, while time-consuming, is navigable with the right preparation.