Fillable N-400 Application for U.S. Citizenship (PDF)

Welcome! If you’re ready to become a U.S. citizen, the Form N-400, Application for Naturalization is the official document you need. Our page offers a fillable PDF that works directly in your browser through the Formize PDF Filler app – no extra software required.

What Is the N-400 Form?

The N-400 is issued by U.S. Citizenship and Immigration Services (USCIS) and is used by lawful permanent residents to apply for naturalization. The form collects personal information, residency history, employment details, and your eligibility for citizenship.

How to Complete the Fillable PDF with Formize

Instead of downloading the PDF and opening it in a separate editor, simply click the "Fill out this form" button below. The Formize PDF Filler app will load the N-400 in a secure, browser‑based editor where you can type, check boxes, and sign electronically.

Common Mistakes to Avoid

• Leaving fields blank: Every required field must be completed; otherwise USCIS will reject the application.
• Mismatched dates: Ensure dates of residence, travel, and employment are consistent throughout the form.
• Incorrect filing fee: Verify the current fee on the USCIS website before submitting.
• Signature issues: Use the digital signature tool in Formize; a handwritten signature scanned later can cause delays.

Where to Submit Your Application

After you finish the form, download the completed PDF, print it (if required), and mail it to the USCIS lockbox address listed in the official filing instructions. You can also submit the form online through the USCIS myUSCIS portal if you prefer an entirely electronic process.

Need Help? Resources & Support

USCIS provides a detailed Instruction Guide for the N-400. For additional assistance, visit the USCIS Contact Center or schedule an appointment at your local office.

Download the official N-400 PDF