USCIS · United States

Fill Form N-400 online — free with AI

Form N-400: Application for Naturalization

Upload your blank Form N-400 from USCIS, let AI auto-detect every field, type or dictate your data, and download the completed PDF in seconds. No watermarks, no install.

Tap to upload your PDF

or browse files — free account required, no credit card

By uploading, you confirm you have the legal right to use this document.

Free to start No watermark Works on any device GDPR compliant

JustFill is not affiliated with USCIS. This is an independent third-party tool to help you complete Form N-400. Always download the current blank form from the official source and verify your completed copy before signing or submitting. Official Form N-400 from USCIS

Quick answer

USCIS Form N-400, Application for Naturalization, is the application a lawful permanent resident (green-card holder) files to become a US citizen. It covers your eligibility basis, residence and travel history, employment, and the good-moral-character questions USCIS reviews. Most applicants qualify after five years as a permanent resident (or three years if married to and living with a US citizen). With JustFill you upload the blank USCIS N-400 PDF, the AI maps every field, and you complete and download it free online.

Form
Form N-400
Issued by
USCIS
Country
United States
Cost to fill
Free

What is Form N-400?

Form N-400 is the USCIS application for US citizenship through naturalization. JustFill makes the long form fillable in your browser. It asks for your biographic details, time as a permanent resident, trips outside the United States, residence and employment history, marital information, and a series of eligibility and good-moral-character questions. After filing, you attend a biometrics appointment and an interview that includes the English and civics tests before taking the Oath of Allegiance.

Who fills out Form N-400?

  • Lawful permanent residents (green-card holders) of at least 5 years
  • Permanent residents married to and living with a US citizen for at least 3 years
  • Certain spouses of US citizens employed abroad, and qualifying US military members
  • Green-card holders aged 18+ who meet continuous residence and physical presence requirements

Field-by-field breakdown

What each section of Form N-400 asks for. JustFill’s AI will detect these fields automatically when you upload the PDF — review the breakdown below so you know what to enter.

Eligibility basis

Whether you qualify under the 5-year rule, 3-year (married to a citizen) rule, military service, or another basis.

Biographic information

Legal name, any name change requested, A-Number, date and country of birth.

Residence & employment

Addresses and jobs for the past 5 years.

Time outside the US

Each trip abroad of 24 hours or more during the relevant period — affects continuous residence.

Marital history

Current and prior marriages, and your spouse's immigration status.

Good moral character

Questions about arrests, taxes, and affiliations USCIS uses to assess eligibility.

Common mistakes to avoid

  • 1Underreporting trips outside the US — long or frequent absences can break "continuous residence" and must be disclosed accurately.
  • 2Answering the moral-character questions carelessly — even minor citations or unpaid taxes must be addressed honestly.
  • 3Applying before meeting the residence requirement (5 years, or 3 if married to a US citizen).

How JustFill helps you complete Form N-400

AI field detection

Upload your blank Form N-400 PDF and our AI maps every fillable region — no manual drawing required.

Save as template

Fill Form N-400 once, save the layout, then reuse it instantly for the next client, employee, or filing.

Your data stays yours

GDPR compliant. Export or delete all your data anytime from your account settings.

Ready to fill Form N-400?

Drop your blank Form N-400 PDF below. Free account, no credit card.

Tap to upload your PDF

or browse files — free account required, no credit card

By uploading, you confirm you have the legal right to use this document.

Frequently asked questions

Generally after 5 years as a permanent resident, or 3 years if you have been married to and living with the same US citizen. You may file up to 90 days before meeting the continuous-residence requirement.
USCIS charges a filing fee, and fee waivers or reductions are available for those who qualify. The form itself is free to download, and JustFill is free to complete it.
The form starts the process; later, at your interview, you take the English and civics (US history and government) tests unless you qualify for an exemption.
Download the current N-400 PDF free from uscis.gov/n-400, then upload it into JustFill to complete it online without printing.

Official source: Form N-400 on USCIS’s website

JustFill is an independent product and is not affiliated with, endorsed by, or sponsored by USCIS or any government agency. Always verify your completed form on the official version before signing or submitting.