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Form N-400 guide (overview)

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A plain-language overview of Form N-400 sections, common mistakes, and the details that often cause delays.

A plain-language overview of Form N-400 sections, common mistakes, and the details that often cause delays.
N-400formularioguíanaturalizacióncómo llenar

Form N-400 is the official application for U.S. naturalization. It asks for a lot of history, but the structure makes more sense once you know what each section is trying to confirm.

Where do I get the form?

Always start from the official USCIS page: uscis.gov/n-400. The form itself is free. Do not pay anyone just to download it.

Main sections of Form N-400

Part 1: Eligibility
You choose the basis for naturalization, such as the five-year rule or the three-year marriage-based rule.

Part 2: Personal information
Your legal name, A-Number, birth information, and other identifying details.

Part 3: Address history
USCIS wants to know where you have lived during the required period.

Part 4: Information about parents
This can help USCIS evaluate whether citizenship may have been acquired through a parent.

Part 5: Employment and school history
List your work history and explain gaps honestly.

Part 6: Trips outside the United States
This section matters a lot because long trips can affect continuous residence and physical presence.

Part 7: Marital history and children
Include all requested family information, even when relatives live outside the United States.

Part 8: Additional yes-or-no questions
These cover legal history, taxes, military service, prior claims to citizenship, and related issues. Accuracy matters here.

Common mistakes to avoid

  1. Using a name that does not match your immigration records
  2. Forgetting short trips abroad
  3. Leaving blanks when a field requires an answer
  4. Guessing instead of confirming dates and addresses
  5. Hiding arrests, citations, or tax issues

Do I need a lawyer?

Many people handle N-400 on their own if the case is straightforward. It is wise to get legal advice if you have:

  • Criminal history
  • Long absences from the United States
  • Complicated marriage history
  • Prior immigration problems
  • Questions about good moral character

CiudadanoUSA helps you practice the kinds of questions USCIS may ask about your N-400 during the interview. Download the app for guided review.