Form N-400, Explained

Understanding the “Application for Naturalization”

What is Form N-400?

Form N-400 (officially called the “Application for Naturalization”) is a government form used by green card holders who are ready to apply for U.S. citizenship after meeting certain eligibility requirements.

Filing this form with U.S. Citizenship and Immigration Services (USCIS), which is part of the U.S. Department of Homeland Security (DHS), is the first step of “naturalization,” the process of becoming an American citizen.

In this guide, we’ll discuss who can and cannot use Form N-400, filing instructions, required documents, and tips for completing your U.S. citizenship application.

For a flat rate of $395, Boundless helps you complete your entire naturalization application, including all supporting documents, independent attorney review, and support from the moment your application is filed until you obtain U.S. citizenship. Learn more, or start your application today.

Not sure if you qualify for U.S. Citizenship?
Start by checking your eligibility.

N-400 Eligibility

Who can file Form N-400?

Only individuals who have satisfied the eligibility requirements for naturalization may file an N-400. In general, you must be at least 18 years old and have had a green card for five years (or three years if you’re married to a U.S. citizen) — unless you’re applying based on qualifying military service. Our guide to naturalization lists all of the basic eligibility requirements for U.S. citizenship.

Who cannot file Form N-400?

You cannot file an N-400 if you:

  • Have not met the eligibility requirements for naturalization.
  • “Acquired” or “derived” citizenship through at least one U.S.-citizen parent or are a child of a U.S. citizen and live abroad (see this guidance from USCIS to learn more).

Not sure if you’re eligible for naturalization? You can check your eligibility on Boundless without providing any personal information. When you’re ready to apply for U.S. citizenship, Boundless can guide you through every milestone of the naturalization process, starting with your N-400 application all the way to the finish line. Learn more, or get started today.

N-400 Basics

How much does it cost to file Form N-400?

The current government fee for filing an N-400 is $725, including $640 for processing and $85 for biometrics services, both nonrefundable whether the application is approved or denied.

Certain applicants, however, are eligible for a reduction or waiver of the fees. (Boundless has a detailed guide on the full cost of naturalization.)

How long does it take to process Form N-400?

The current average processing time for naturalization applications is a little over 10 months.

Generally, however, the speed of processing depends on the USCIS field office handling the application, and some applicants can get a head start on the process (see “Filing Early” below). Our detailed guide to the U.S. citizenship timeline has more details on what to expect during each stage of the naturalization process.

Can I file my N-400 online?

Yes, you may file your N-400 online unless you are applying from abroad or are applying for a fee reduction or waiver, in which case you must use the paper Form N-400 and file by mail.

To apply online, you must create an online account with USCIS and sign your application electronically (by typing your full name at the end of the application).

Where should I send my N-400 form?

Where you must send your N-400 application and materials depends on whether you file online or by mail. If you’re filing by mail, the USCIS address to send your materials to will depend on the state in which you live and the delivery service you choose (U.S. Postal Service vs. FedEx, UPS, or DHL).

If you’re applying based on your (or your family member’s) military service, you will send your N-400 materials to a special address, depending also on the delivery method you choose.

USCIS provides a list of the addresses to which applicants must send their N-400 (see “Where to File” tab).

IMPORTANT: Make sure to make a copy of your completed N-400 before you submit it to USCIS. Your citizenship interview will focus largely on the answers you provided on your naturalization application. It’s important to review those answers prior to attending your interview.

Boundless turns all the government requirements for naturalization into simple questions you can answer online, typically in under an hour — compared with days or weeks the traditional way. We make it easy to complete your naturalization application and avoid common problems. Learn more, or get started today.

Filing Early

The 90-day early-filing rule: You may file your naturalization application with USCIS as early as 90 days before the end of your three- or five-year wait period as a green card holder — as long as you’ve met all other eligibility criteria. (Boundless has a detailed guide on naturalization eligibility requirements.)

To determine your early-filing date, you must find the date on your green card (officially called a “Permanent Resident Card”); add three or five years, whichever is applicable; then subtract 90 days. (USCIS provides a calculator to help you determine your 90-day early filing date. For the “Anniversary Date,” you’ll need to enter the date that is three or five years from the date on your Permanent Resident Card.)

Let’s assume, for instance, that you’re a green card holder with no special circumstances, in which case your wait period is five years. If the date on your Permanent Resident Card is January 1, 2013, then you become eligible for naturalization on January 1, 2018. Ninety days before that would be October 3, 2017, which is the earliest date you’d be able to file.

IMPORTANT: You cannot actually become a U.S. citizen until after you’ve waited the full three or five years. Filing early just gives you a head start on the process.

When completing your naturalization application through Boundless, you’ll simply answer a series of questions online — typically within just an hour (compared with days or weeks the traditional way) — and the completed forms arrive at your doorstep. Let’s begin!

N-400 Required Documents

All naturalization applicants must include supporting documents with their Form N-400. If you file your application online, you will need to upload digital copies (scans or photos) of these documents to your online USCIS account.

What documents do I need to send with my N-400?

Required documents for all applicants include:

  • A copy of your green card (Form I-551, officially called the “Permanent Resident Card”)
  • Application fee payment (by check or money order, with your A-Number written on the back, or by credit card using Form G-1450)

Some applicants must submit additional supporting documents with their N-400, based on their particular circumstances, including:

  • Proof of your current marital status, if you’re married or were previously married (marriage certificate, divorce papers, annulment certificate(s), and/or death certificate(s) for former spouses)
  • Two 2-inch-by-2-inch passport-style photos, if you live and are applying from abroad
  • Form N-426, officially called the “Request for Certification of Military or Naval Service,” if you’re applying for based on your military service
  • Form N-648, officially called the “Medical Certification for Disability Exceptions,” if you’re applying for an exemption to the U.S. citizenship test based on a qualifying medical condition

Filing your application package is only the first step of the naturalization process. It could be several months or more until you obtain U.S. citizenship. Boundless will guide you through to the end, helping you stay on top of interview preparation, follow-on forms, and every other important milestone along the way. Ready to start your application?

N-400 Filing Tips

You can follow these tips to help ensure a smooth N-400 application process (if you’re filing by mail):


Do use black ink only. USCIS is very particular about the color of ink used to complete an application, which is why it’s best to fill out the form electronically then print it afterward or use a service like Boundless, which will print out all your forms and documents, assembled precisely how the government prefers (learn more about our services). If you decide to complete your application by hand, make sure to use the correct color of ink to prevent any delays.

Do review your Form N-400 before filing. It’s important to make sure that all of your answers are correct and all supporting documents are included with your application before you send your materials to the U.S. government. Any missing information or document could delay processing. Worse, it could lead to a denial of your application — based on a new USCIS policy that raises the stakes of completing immigration applications accurately the first time — which means you would need to go through the process again and pay the filing fee a second time.

Do provide translations. If any of your supporting documents was produced in a language other than English, you will need to obtain a certified English translation of that document with your N-400 application.


Don’t clutter your form. Do not highlight, cross out, or type or write beyond the space provided for your answer. If you need to correct your answer to a question, it’s best to complete a fresh N-400 form. USCIS prefers this instead of using correcting fluid or tape to correct an error. USCIS scans information from the application, and their machines may detect text that’s covered by the correcting fluid or tape, which could potentially lead to errors and processing delays.

Don’t submit unnecessary paperwork. The Form N-400 instructions will clearly indicate which documents are required to be submitted as photocopies versus originals. If you submit original copies of documents that USCIS did not specifically request or require, you may not get these back, as USCIS may destroy them immediately upon receiving them.

Don’t forget to sign! If your signature is missing from your application when USCIS receives it, they will most likely reject (that is, refuse to accept) your application and ask you to send a new one. A recent USCIS policy change, however, makes it imperative to follow all USCIS instructions carefully, as a single mistake or missing document could lead to a denial of your application. That means you would need to re-apply and pay another $725 to process your paperwork (unless you qualify for a fee reduction or waiver).

With Boundless, you get an independent immigration lawyer who will review your entire application package to make sure it’s accurate and complete. Only after this independent lawyer has confirmed the readiness of your application package will Boundless mail it to you for filing with the federal government. The attorney will also answer any extra questions you might have — for no additional fee. Learn more, or start your application today!

Frequently Asked Questions

What should I do if I’ve moved since filing my application?

If you move after filing your N-400, you must notify USCIS within 10 days of relocating to your new address. This ensures that you will not miss any notices that USCIS sends to you by mail. (See the USCIS website for address-change instructions.)

I’m currently in college. What should I put down on my application as my physical and mailing addresses?

The current physical address that you’ll need to use depends on where you plan to attend your future citizenship interview and exam appointment. The location of your appointment will be determined by your ZIP code. If, for instance, you attend college in San Antonio, Texas but live in Houston, you would need to provide your ZIP code in San Antonio if you want to attend your interview and exam at the USCIS field office in San Antonio or your ZIP code in Houston if you prefer the Houston field office.

As for your mailing address, you must use the address where you’d like to receive all written correspondence from USCIS. Because these letters contain sensitive information, many people prefer to use their actual home address to receive their mail. In our example above, for instance, you may find it more comforting to receive these letters at your home address in Houston rather than at a temporary school address, especially if you’ll be leaving school within the next couple of years.

Boundless — for people who want the expertise
of an immigration lawyer, not the price tag.