How to Fill Out the N-400 Application for Naturalization

The N-400 is the form you file to become a U.S. citizen. This step-by-step guide explains every major section, what mistakes to avoid, and how to submit it correctly.

By Marcus G. Bastawros, MBA · Published 2026-05-04 · Updated 2026-05-04

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The N-400, Application for Naturalization, is the official form you submit to USCIS to begin the process of becoming a U.S. citizen. It is 20 pages long and asks detailed questions about your background, residency, travel history, and moral character. Filling it out correctly is critical — errors or omissions can delay your application or trigger a denial. This guide walks you through every major section.

Part 1 — Your Name and Contact Information

Enter your legal name exactly as it appears on your Permanent Resident Card (Green Card). If your name has ever been different — through marriage, divorce, or legal change — list every prior name in Part 2. USCIS will compare your application to immigration records and inconsistencies raise red flags.

If you want to change your name at the time of naturalization (many applicants do), write the new desired name in Part 3. The federal court can officially change your name during the oath ceremony at no extra cost — a significant saving compared to a separate court filing.

Part 4 — Information About Your Residence

You must list every address where you have lived for the past five years (or three years if applying based on marriage to a U.S. citizen). Include the full street address, city, state, zip code, country, and the dates you lived there. Gaps in your address history are one of the most common errors — account for every month.

Part 5 — Information About Your Parents

This section determines whether you may already be a U.S. citizen through a parent and therefore do not need to naturalize at all. If one or both of your parents is a U.S. citizen, review INA § 320 before filing. Some people have automatic citizenship without knowing it.

Part 7 — Time Outside the United States

List every trip you took outside the U.S. that lasted 24 hours or more during the past five years (or three years). For each trip, provide the departure date, return date, destination, and purpose. USCIS will compare your answer to travel records — inaccuracies here are a common cause of delays and denials.

Part 8 — Information About Your Employment

List all employers for the past five years, including self-employment and periods of unemployment. If you were unemployed, write 'Unemployed' and list the dates. Do not leave gaps — every month must be accounted for.

Parts 11–12 — The Good Moral Character Questions

These are the yes/no questions that ask about arrests, criminal history, taxes, selective service registration, prior immigration violations, membership in organizations, and more. Answer every question truthfully. USCIS conducts background checks and FBI fingerprinting — if your answers conflict with records, it is treated as misrepresentation, which is a far more serious problem than the underlying issue.

If you answer 'Yes' to any question, USCIS will ask you to explain during the interview. A 'Yes' answer does not automatically disqualify you — the context and severity matter. But lying does.

Part 14 — Signature and Certification

Sign the form in black ink. If you use a preparer or interpreter, they must complete Parts 15 and 16. Do not sign until the form is entirely complete — changes after signing must be initialed.

Where and How to File

• File online at my.uscis.gov (fastest processing; you can check status online)
• Mail a paper form to the USCIS lockbox that serves your state (listed in N-400 instructions)
• Include Form G-1450 if paying the filing fee by credit card (paper filers)
• Do not staple documents — use binder clips
• Keep a complete copy of everything you submit

Biometrics and What Happens After Filing

After USCIS receives your N-400, you will get a receipt notice (Form I-797) within a few weeks. You will then be scheduled for a biometrics appointment where USCIS takes your fingerprints and photo. After biometrics, you wait for your interview date. Use that waiting period to study for the civics test — most interview dates come 6 to 18 months after filing, depending on your field office.

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