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

The N-400 is the official United States Citizenship and Immigration Services (USCIS) form used to apply for naturalization. By using Formize’s fillable PDF, you can complete the entire application directly in your browser—no extra software required.

Our online PDF filler automatically saves your entries, validates required fields, and lets you download a clean, printable version ready for submission. This saves time, reduces errors, and helps you meet USCIS filing standards.

Below you’ll find everything you need to know about the N-400 form, from eligibility requirements to step‑by‑step instructions for a flawless submission.

What Is the N-400 Naturalization Form?

The N-400 collects personal information, residency history, employment details, and background data required by USCIS to determine if you qualify for U.S. citizenship. It replaces the older paper‑only process, and the PDF version is fully fillable when opened with a PDF reader or an online filler like Formize.

How to Complete the Fillable N-400 Online

Follow the simple steps in the “How‑To” section below. The process takes about 30‑45 minutes if you have all documents on hand.

Common Mistakes to Avoid on Your Citizenship Application

• Leaving required fields blank – Formize will highlight missing answers before you can download.
• Using the wrong edition of the form – always use the latest PDF (linked on this page).
• Submitting original documents unless specifically requested – attach only copies and translations.
• Incorrect date formats – USCIS requires MM/DD/YYYY.

Where to Submit Your Completed N-400

After you download the completed PDF, you can either file it online through your USCIS account or mail it to the correct USCIS Direct Filing Address for your state. The address list is available on the USCIS website.

Eligibility Checklist for Naturalization

• Be a lawful permanent resident for at least 5 years (or 3 years if married to a U.S. citizen).
• Maintain continuous residence and physical presence in the U.S.
• Demonstrate good moral character.
• Pass English and civics tests (or qualify for an exemption).

Having this checklist handy while you fill out the N-400 will ensure you provide all required information the first time.