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Form N-400, Explained

Form N-400, Explained

Understand the timeline, cost, and requirements for the “Application for Naturalization”

What is USCIS Form N-400 (U.S. Citizenship)?

Form N-400, officially called the “Application for Naturalization,” is a government form used in the United States. It’s the first step if you’re a green card holder who wants to become a U.S. citizen through a process called naturalization. This process has specific eligibility requirements. After meeting those requirements, you’ll submit the N-400 to the U.S. Citizenship and Immigration Services (USCIS) to officially apply for U.S. citizenship.

Important:

March 4, 2025: USCIS has updated Form N-400, removing the option for a gender identity other than male or female. Previously the form had the option to mark either “female,” “male,” or “another gender identity.” Now, applicants will only have the option to mark either “female” or “male.”

USCIS has eliminated the backlog of citizenship applications, and processing times have continued to improve since the pandemic. Currently, the average time to get Form N-400 approved is about 5.5 months, and the N-400 form costs $760 when you file.

N-400 Timeline

How long is N-400 taking now?

The current median processing time for Form N-400 is around 5.5 months (Boundless updates this timeline on a monthly basis). USCIS has prioritized naturalization applications in recent years, and has cut the N-400 approval time in half, since 2019.

Generally, 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.

How long do I have to wait to apply for citizenship after I get my green card?

Usually, someone who is not a citizen needs to live in the U.S. as a lawful permanent resident for at least 5 years to apply for citizenship. However, if they are married to a U.S. citizen, they only need to be a resident for 3 years. According to USCIS data, the average time of marriage before applying for citizenship is 7 years.

Understanding the 90-day early-filing rule for naturalization

If you’ve been a green card holder for the required time (usually 3 or 5 years), you may be able to file your naturalization application up to 90 days early!

Here’s how to figure out your earliest filing date: 


  • ︎Find Your Green Card Date: Look for the date your Permanent Resident Card was issued.
  • Add the Wait Period: Add either 3 or 5 years (depending on your eligibility) to the Green Card date. That’s the date you generally become eligible to naturalize.
  • Subtract 90 Days: Go back 90 days from your eligibility date. This is the earliest you might be able to file Form N-400.
  • Example: Green Card Date (Jan 1, 2025) + Wait Period (5 years) = Eligibility Date (Jan 1, 2030); Earliest Filing Date: October 3, 2029

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, and 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, 2025, then you become eligible for naturalization on January 1, 2030. Ninety days before that would be October 3, 2029, which is the earliest date you’d be able to file.

(Boundless has a detailed guide on naturalization eligibility requirements.)

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 in the process.

Required documents for Form N-400

When you apply for U.S. citizenship with Form N-400, you’ll need to include some supporting documents as evidence that you’re eligible to naturalize.

USCIS requires the following documents to prove an applicant’s eligibility for naturalization, to verify identity, to run background checks, and to make the process fair for everyone.

  • Proof of Residency
    • Green Card: Provide a photocopy of both sides of your Permanent Resident Card (Form I-551).
    • Lost Green Card: If it’s lost, include a photocopy of your Form I-90 receipt (Application to Replace Permanent Resident Card).
  • Payment for Fees
    • Required Fees: .
    • Payment Methods: Submit a check or money order with your A-Number on the back, or use a credit card (Form G-1450).
  • Photographs (if residing outside the U.S.)
    • Two Identical Photos: Include two color photos following USCIS guidelines (available on their website).
    • Photo Details: Write your name and A-Number lightly in pencil on the back of each photo.
    • Religious Head Coverings: Ensure your face is clearly visible for identification.

Additional supporting documents for Form N-400

Depending on the situation, some applicants must submit additional supporting documents with their N-400:

  • If your name is different than what is on your green card, send documents like your marriage certificate, divorce decree, or court documents showing the name change.
  • If you’re applying based on your marriage to a U.S. citizen you must send the following four documents:
    • Evidence your spouse has been a U.S. citizen for the last three years
    • Evidence of your marital status (marriage certificate)
    • Copies of divorce papers, annulment papers, or death certificates if you were previously married
    • Documents related to you and your spouse (e.g., shared tax returns, bank statements, rental agreements, children’s birth certificates)
    • Official joint tax returns from the last three years
    • IRS records of your tax filings for the past three years
  • If you’re in the U.S. military and applying for citizenship based on your service, include Form N-426.
  • If you’ve been outside the U.S. for 6 months or more, send evidence that you kept ties to the U.S., like tax returns or mortgage payments.
  • 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.

Boundless Tip

Even if you’re missing some documents, you can still get a head start on your application by beginning to fill out the N-400 form itself, and gathering what is readily available. Boundless can help you get started on the forms and tell you exactly what evidence to gather along the way.

If you file your application online, you will need to upload digital copies (scans or photos) of these documents to your online USCIS account.

Boundless has helped more than 100,000 people with their immigration plans. We’ll be your visa planning partner from beginning to end. Get started today!

N-400 Cost

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

The government fee for filing an N-400 is $760. However, there are additional costs to consider as you plan, including application assistance, translation services, photocopying and mailing costs, and potential reapplication costs if your application is 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.)

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).

Boundless helps you build a tailored visa plan for every step of the process, from forms to your immigration interview. Get started today!

N-400 Application Process

Here’s the step-by-step process for filing an N-400, with specific milestones and actions to plan for along the way.

  • Review the eligibility requirements and ensure meet the age, residency, good moral character, and other requirements.
  • Gather supporting documents and check the USCIS website for current requirements specific to your situation
  • Carefully fill out Form N-400, ensuring you provide accurate and complete information.
  • Submit your application – you can do this either online or by mail.
  • After filing Form N-400, you’ll receive a notice with the date, time, and location of a biometrics appointment. At the appointment, you’ll have your fingerprints and photographs taken.
  • You’ll then be scheduled for an in-person interview with a USCIS officer; during the interview, you’ll also take the U.S. immigration civics test.
  • USCIS will review your whole case and inform you of their decision, if approved, you’ll be invited to a formal oath ceremony to officially become a U.S. citizen.

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.

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 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).

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’s:

  • 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. 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’ts:

  • 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 $760 to process your paperwork (unless you qualify for a fee reduction or waiver).

Form N-400 FAQs

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.

After you file Form N-400, USCIS will send you an appointment notice for your interview. Usually lasting around 20 minutes, the interview is the chance to verify the information you have sent through with your application. The officer may also ask a few questions about your background. Boundless has prepared a guide to help you prepare for your citizenship interview.

Yes, as long as you comply with the requirements of the VWP, you can travel outside the U.S. and re-enter. However, the total duration of your stay in the U.S. cannot exceed 90 days within a 180-day period.

If you are married to a U.S. citizen and have been living in the U.S. as a permanent resident for at least three years, you may be eligible to file Form N400 to become a U.S. citizen. If you became a permanent citizen through another category, then you may have to wait roughly five years before you can naturalize.

If you are a green card holder who is

and ready to apply for U.S. citizenship, you may file Form N-400 to USCIS to apply for naturalization.

If you are not currently a U.S. citizen, but one or both of your parents are, you may file Form N-600 (Application for Certificate of Citizenship) to apply for your citizenship. To be eligible, you must be under the age of 18 and currently be in the U.S. If you are outside of the U.S., you may apply for a passport through the U.S. State Department.

If you have filed Form I-751 (Petition to Remove Conditions on Marriage) to apply for a full green card after your conditional green card, it’s possible you may become eligible to apply for naturalization while your I-751 is still being processed.

If this happens, you can still file Form N-400. With your application though, you should include the notice of receipt USCIS sent to confirm they were processing your I-751 petition, called Form I-797 (Notice of Action).