N-400 Application for U.S. Citizenship – Fillable PDF

Why Use a Fillable PDF for Your N-400?

The N-400 is the official Application for Naturalization used by the United States Citizenship and Immigration Services (USCIS). A fillable PDF lets you type directly into the form, reduces errors, and speeds up processing.

How to Complete the N-400 with Formize

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 loads in your browser, giving you a clean, interactive workspace.

Follow the step‑by‑step guide below to finish your application online.

Common Mistakes to Avoid on Your Citizenship Application

• Leaving required fields blank or entering “N/A” when information is not applicable.
• Using an unofficial version of the N-400 that lacks fillable fields.
• Submitting an outdated version of the form (always use the latest PDF from USCIS).
• Failing to sign and date the form electronically before saving.

Where to Submit Your Completed Form

After you have saved the completed N-400, print it, sign the hard copy, and mail it to the USCIS lockbox address listed in the form instructions. You can also submit the electronic version through your USCIS online account if you prefer.

Need More Help?

Review the official USCIS instructions included with the PDF or visit the USCIS N-400 page for detailed guidance.