US Citizenship Application (Form N‑400) – Fillable PDF

Applying for United States citizenship is a major step, and the official Form N‑400, Application for Naturalization is the gateway. With Formize’s fillable PDF you can complete the entire form directly in your browser—no extra software required.

Our online PDF filler loads the exact version of the USCIS N‑400 form, preserving the official layout while allowing you to type, select checkboxes, and attach digital signatures. When you’re ready, simply download the completed PDF and submit it to USCIS.

What Is Form N‑400?

Form N‑400 is the United States Citizenship and Immigration Services (USCIS) document used by permanent residents to apply for naturalization. The form collects personal information, residency history, employment details, and answers to eligibility questions.

Key Sections & Required Documents

• Personal Information: name, address, Social Security number, and contact details.
• Residence & Employment History: dates and locations for the past five years.
• Eligibility Questions: criminal background, tax obligations, and military service.
• Supporting Documents: copy of your green card, passport‑style photos, tax transcripts, and proof of continuous residence.

How to Fill Out the Form Online

Instead of downloading the PDF and opening it in a separate editor, simply click the "Fill out this form" button on this page. The Formize PDF Filler app will load automatically. Follow the on‑screen prompts, save your progress, and export the finished document when you’re done.

Common Mistakes to Avoid

• Leaving any required field blank—USCIS will reject incomplete applications.
• Providing outdated addresses or employment dates.
• Forgetting to sign and date the form electronically.
• Submitting the wrong version of the N‑400 (always use the latest PDF from USCIS).

Where to Submit Your Application

After completing the form, print the PDF (or keep the digital copy) and mail it to the USCIS Lockbox address listed in the USCIS filing instructions. You can also submit the form online through the USCIS myUSCIS portal if you prefer a fully electronic filing process.

Need help? Review the USCIS official instructions for detailed guidance on each section.