Form N-400: Definition, Requirements, Application, and Processing TimeForm N-400 is known as “Application for Naturalization”. Form N-400 is the immigration document used to file for US Citizenship. Form N-400 is typically filed by foreign citizens who have been Lawful Permanent Residents (LPRs) for at least 3 or 5 years. Approval of your N 400 form allows you to vote in US federal elections, sponsor your immediate family for Permanent Residence, obtain automatic USA Citizenship for your children, and own a US passport. 

The key requirements for N 400 application include your Permanent Resident Card (Green Card), proof of payment of the N-400 filing fee, and identity photos if you are applying from outside the United States. The N-400 processing time takes between 18 and 24 months and starts from your N-400 form filing date up until you take your Oath of Allegiance. Taking the Oath of Allegiance to the United States demonstrates that you honor the U.S. Constitution and pledge to perform your duties as a Naturalized American Citizen. 

What is Form N-400?

Form N-400 is also known as “Application for Naturalization. N-400 is used to file for US Citizenship by eligible foreign citizens. Form N-400 is submitted to the U.S. Citizenship and Immigration Services (USCIS) upon meeting qualifying criteria such as length of Permanent Residence in the US, marriage to a U.S. Citizen, or service in the US military. 

How Does Form N-400 Work?

Form N 400 is filed to initiate the process of Naturalization for persons who have not acquired U.S. Citizenship through birth. Form N 400 is generally applied for after holding a Green Card for at least 3 or 5 years. A Green Card (Permanent Resident Card) allows foreign citizens to live, work, and study permanently in the United States. Approval of your N400 application makes you an American Citizen with added benefits such as the right to vote and own a USA passport in addition to permanent residence in the United States.

What are the Benefits of Form N-400?

Most U.S. Permanent Residents opt to file for the N-400 form to become Naturalized US Citizens. Applying for Naturalization involves voluntarily choosing to become an American to obtain the following benefits that are not accessible to Green Card holders. 

  • Gain the right to vote. Voting rights for US citizens include the ability to participate in both federal elections and local elections.
  • Run for public office. You are able to run for federal, state, and local public offices as a Naturalized USA Citizen.
  • Do away with immigration forms and Green Card renewal. Becoming a US Citizen through Naturalization means you no longer have to apply for Green Card renewal every 10 years and pay the fees. You are able to relocate anywhere in the United States without the need to inform the US government as a Naturalized American.
  • Obtain employment in the US government. An approved Naturalization makes you employable in the U.S. government and entails better benefits and higher pay than working for private businesses.
  • Have greater accessibility to government assistance. As an American citizen, there are no longer any restrictions on your eligibility for federal programs like Social Security and Medicare. You are qualified for federal financial aid for college education which is available only to Citizens of the US.
  • Petition your immediate family for Green Cards. As a naturalized American, you are able to sponsor your siblings, parents, and adult children in addition to your spouse and young children for a Green Card. There is no annual cap on immigrant visas for immediate family members of US Citizens.
  • Obtain American citizenship for your children. Children of Naturalized Citizens are automatically U.S. Citizens even if they were born outside the United States. You only need to inform the nearest U.S. embassy or consulate to establish your child’s American Citizenship. 
  • Gain protection from deportations. Like any other US Citizen, you cannot be forcibly deported from the country even if you are arrested or convicted. Only when a USA Citizen’s Naturalization has been revoked, which happens very rarely, can that person be deported. The initial Application for Naturalization must be fraudulent in the first place for this to occur.
  • Own a US Passport. The ability to travel to more than 180 countries and territories without a visa is one of the main benefits of becoming a Citizen of the United States. As an American citizen, you are no longer subject to limitations on the length of time or frequency of your international travel.

What are the Risks of Form N-400?

Aside from knowing the advantages and rights you gain when filing N 400 form, you also need to be aware of the potential risks that come with a Naturalization application.

  • Risk of failing the Naturalization tests. USA Citizenship through Naturalization requires passing an English proficiency and civics test. You will have to demonstrate that you are able to write, speak, and read basic English during your N 400 application interview. The civics test measures your knowledge and understanding of American history and its government. 
  • Risk related to criminal convictions. You need to undergo a biometrics screening and background check to evaluate your criminal history in the US and in other countries. You need to demonstrate good moral character to be granted Naturalized U.S. Citizenship. 
  • Risks related to continued residence and travel outside the US. You need to have lived physically in the USA for at least 30 months to qualify for N-400 Naturalization. Avoid traveling outside the United States for more than 6 months to ensure you maintain your Permanent Resident status and remain qualified for US Citizenship Naturalization.
  • Risk related to fraudulent applications. Not only will your N400 form be screened for fraud but also your past Green Card and immigration applications. Fraud assessment does not only cover your immigration history but also the background of your sponsor for Permanent Residency. Make sure that all information and evidence you submit are accurate and true as both unintentional and intentional fraud offenses make you ineligible for Naturalization. 
  • Risk on tax payment issues and financial obligations. The N400 form asks whether you have failed to pay your taxes as a Permanent Resident and whether you have corresponded with the Internal Revenue Service (IRS) or the appropriate federal, state, or local authorities. Failing to support your dependents is also a risk for N 400 application denial. 
  • Risks related to security issues. You need to pledge obedience and loyalty to the U.S. Constitution as part of the Naturalization process. Membership in Communist or totalitarian parties and involvement in activities that endanger US national security disqualifies you from US Naturalization.
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How Does the N-400 Form Look Like?

The N-400 application form is composed of 20 pages with 18 parts. Form N 400 is downloadable from the U.S. Citizenship and Immigration Services (USCIS) website together with the N 400 instructions.

How to Fill out N-400 Application for Naturalization?

USCIS Form N-400 instructions include using only blank ink and answering the questions completely and accurately. Mistakes made while filling out N400 require accomplishing a new USCIS N 400 form instead of using correction tape or fluid. You need to submit all pages of the N-400 form and write your A-Number on the top right corner of each page. 

Here we discuss each part of the USCIS N 400 form and highlight the important Form N 400 instructions and required information.

Part 1: Information About Your Eligibility

You need to specify your eligibility category for US Naturalization. You are either a lawful permanent resident (LPR) for 5 years, a spouse of a US Citizen and Green Card holder for 3 years, or a member of the US military. 

Part 2: Information About You

Information in this section includes your legal name, other names you have used, US Social Security Number (SSN), gender, date of birth, and country of birth and citizenship. This section also asks whether you have a disability or qualify for exemption from the English language test based on age.

Part 3: Accommodations for Individuals with Disabilities and/or Impairments

This section is for persons with disabilities that require special accommodation in completing the Naturalization application. You need to specify your disability and/or impairment as well as the accommodations you are requesting from USCIS. 

 Part 4: Information to Contact You

You need to write down your current telephone number/s and email address.

Part 5: Information About Your Residence

All addresses that you have lived in during the past 5 years both in the US and outside the US must be indicated in your Form N400. Give your current mailing address if it is different from your residential address. 

Part 6: Information About Your Parents

You have to specify whether your mother and/or father are USA Citizens. Applicants with a US Citizen parent will need to provide the legal name, country of birth, and A-Number of their US Citizen parent. 

Part 7: Biographic Information

Biographic information covers your ethnicity and race, height, weight, eye color, and hair color.

Part 8: Information About Your Employment and Schools You Attended

List all your schools and workplaces in the last 5 years whether part time or full time, including military, police, or intelligence services. Start with your current and most recent work, studies, or unemployment.

Part 9: Time Outside the United States

You need to disclose the total number of days and the total number of trips outside of the United States you had in the past 5 years. You need to list the countries you traveled to starting from the most recent one.

Part 10: Information About Your Marital History

Indicate your current marital status and whether you have had prior marriages. Write whether your current spouse is a U.S. Citizen or a current member of the U.S. Armed Forces. 

Part 11: Information About Your Children

Detail how many children you have whether alive, missing, or deceased. Specify the country of their birth, age, and residence. Include your current stepchildren, legally adopted children, and children born to you when you were not married.

Part 12: Additional Information About You

This section consists of questions answerable by yes or no. Questions include your history of voting registration, owed taxes, membership in Communist or totalitarian parties, involvement in genocide or torture, and participation in vigilante or guerilla groups. This section also asks about your criminal offenses, sentences, and rehabilitation programs. Other questions are on your immigration history and involvement with the US military. You also need to pledge your support for the US Constitution and Government as well as your willingness to take the Oath of Allegiance. 

Part 13: Applicant’s Statement, Certification, and Signature

You have to make a statement about whether you filled the N 400 form yourself or engaged the services of an interpreter and/or preparer. You then need to read through the certification and affix your signature.

Part 14: Interpreter’s Contact Information, Certification, and Signature

The interpreter has to fill out this section of the USCIS N 400. The interpreter’s name, mailing address, contact information, certification, and signature must be given.

Part 15: Contact Information, Declaration, and Signature of the Person Preparing this Application, if Other Than the Applicant

The preparer has to write their full name, mailing address, and contact information. The preparer must fill out the statement, read the certification, and affix their signature in this section of UCSIS N-400.

Part 16: Signature at Interview

You need to affirm that all information on your N 400 application is correct and complete. You only need to sign this section during your US Citizenship interview.

Part 17: Renunciation of Foreign Titles

Persons with a hereditary title or order of nobility have to renounce their title during the US Citizenship ceremony. 

Part 18: Oath of Allegiance

This section is completed only during the interview. Approval of your N-400 application requires you to take the Oath of Allegiance to complete the process of getting USA Citizenship through Naturalization.

How Much Does Form N-400 Application Cost?

The N-400 filing fee is $640 to apply for Naturalization for American Citizenship. An additional biometrics fee of $85 is required for applicants under 75 years old. Military applicants do not need to pay the N 400 fee and biometrics fee. Make sure to pay the correct amount for the N 400 application fee as USCIS rejects incorrect payments. The cost of N400 application is paid via money order, check, or credit card.

Form I-912 is used to apply for N 400 fee waiver for applicants who are unable to pay for the application costs. Your total annual household income must be between 150% and 200% of the Federal Poverty Guidelines to qualify for an N 400 fee waiver. Form I-912 is also known as “Request for Fee Waiver”.

What are the Documents Required for N-400?

The documents required by USCIS must be submitted together with Form N 400. Here is your N-400 checklist for USA Naturalization.

  • Copy of the front and back of your Green Card (Permanent Resident Card).
  • The check or money order for the N 400 filing fee and biometrics fee.
  • 2 identical photos with your name and A-Number written lightly with a pencil on the back of each photo for applicants outside the US.
  • A copy of the original Form G-28 if an attorney or accredited representative is acting on your behalf. Form G-28 is known as “Notice of Entry of Appearance as Attorney or Representative”.
  • Document showing a legal change of name such as a marriage certificate, divorce decree, or court document.
  • For applicants filing Naturalization based on marriage to a US Citizen, below are the needed evidence.
    • Proof that your spouse has been a US Citizen for the past 3 years such as a Certificate of Naturalization, Certificate of Citizenship, or FS-420 (Report of Birth Abroad of a Citizen of the United States of America).
    • Your current marriage certificate.
    • Evidence of termination of all prior marriages of your spouse.
    • Documents showing your relationship with your spouse such as tax returns, leases, mortgage statements, or birth certificates of children.
  • Evidence that your prior marriages have ended such as divorce decree/s, annualment/s, or death certificate/s.
  • Proof that you maintained ties to the USA if you traveled outside the US for more than 6 months after gaining Lawful Permanent Residence (LPR).
    • An Internal Revenue Service (IRS) transcript or certified tax return listing tax information for the past 5 years.
    • Rent or mortgage payment and pay stubs. 
  • Proof of financial support for dependent children that do not live with you such as money and receipts, court or agency printout of child support payments, or a letter from the parent or guardian caring for your child(ren).
  • For documentation related to criminal history, provide the following.
    • An original official statement by the arresting agency for arrests or detainment wherein no charges were filed.
    • An original or court-certified copy of the complete arrest record and disposition for arrests or detainment wherein charges were filed such as a dismissal order, conviction record, or acquittal record. 
    • An original or court-certified copy of the court order for arrests or convictions that have been vacated, set aside, sealed, expunged, or otherwise removed from your record. 
    • Original or court-certified copy of the sentencing record and probation or parole record for completed alternative sentencing or rehabilitative programs.
  • For owed taxes, file the following with your N-400 form.
    • Internal Revenue Service (IRS) correspondences if you failed to file an income tax return since becoming a Lawful Permanent Resident (LPR).
    • A signed agreement from the Internal Revenue Service (IRS) or state or local tax office if you have any federal, state, or local taxes that are overdue.
  • The original and completed Form N-426 for applicants seeking American Citizenship through US military service. Form N-426 is known as “Request for Certification of Military or Naval Services”.
  • An original Form N-648 for foreign citizens applying for a disability exemption to the Naturalization tests. Form N-648 is known as “Medical Certification for Disability Exceptions”.
  • A “Status Information Letter” from the Selective Service if you did not register with the Selective Service, are male aged 26 years or older, and lived in the USA in a status other than a lawful nonimmigrant between the ages of 18 and 26.

Where can I File my N-400?

Form N400 is filed with USCIS by mail or online. You need to create your USCIS online account for online application which allows you to pay online, check your case status, receive notifications and updates, respond to requests for evidence, and manage your contact information and address.

Filing Form N-400 by mail depends on where you are located.

Your location Mailing address


District of Columbia






New Hampshire

New Jersey

New York

North Carolina


Rhode Island

South Carolina



West Virginia

USCIS Elgin Lockbox

U.S. Postal Service (USPS):

Attn: N-400 
P.O. Box 4060
Carol Stream, IL  60197-4060

FedEx, UPS, and DHL deliveries:

Attn: N-400 (Box 4060)
2500 Westfield Drive
Elgin, IL 60124-7836



American Samoa


Armed Forces Americas

Armed Forces Europe

Armed Forces Pacific



Commonwealth of the Northern Mariana Islands






Marshall Islands







New Mexico

North Dakota



Puerto Rico

South Dakota


U.S. Virgin Islands




USCIS Phoenix Lockbox

U.S. Postal Service (USPS):

Attn: N-400
P.O. Box 21251
Phoenix, AZ 85036-1251

FedEx, UPS, and DHL deliveries:

Attn: N-400 (Box 21251)
2108 E. Elliot Rd.
​​​​​​​Tempe, AZ 85284-1806





USCIS Dallas Lockbox

U.S. Postal Service (USPS):

Attn: N-400
P.O. Box 660060
Dallas, TX 75266-0060

FedEx, UPS, and DHL deliveries:

Attn: N-400 (Box 660060)
2501 S State Hwy 121 Business
Suite 400
Lewisville, TX 75067-8003








USCIS Chicago Lockbox

U.S. Postal Service (USPS):

Attn: N-400
P.O. Box 4380
Chicago, IL 60680-4380

FedEx, UPS, and DHL deliveries:

Attn: N-400 (Box 4380)
131 S. Dearborn, 3rd Floor
Chicago, IL 60603-5517

How Long is the Processing Time for N-400?

The N-400 processing time for Naturalization is between 18 and 24 months. The N 400 processing time starts from the date of filing your Form N400 up until you attend your Oath of Allegiance ceremony.

What are Form N-400 Approval Statistics?

USCIS has Naturalized over 7.4 million applicants in the last 10 years. The top 5 countries that received N 400 approvals in FY 2021 are Mexico (13.9%), India (7.0%), the Philippines (6.0%), Cuba (5.9%), and the Dominican Republic (3.4%).

Below are the latest Form N-400 approvals for FY 2021 up to the 1st quarter of FY 2022 according to USCIS.

Fiscal year per quarter Number of approved Form N-400 applications
October 1 – December 31, 2020 136, 332
January 1 – March 31, 2021 197, 210
April 1 – June 30, 2021 229, 608
July 1 – September 30, 2021 237, 421
October 1 – December 31, 2021 195, 050

Who is Eligible for Filing Form N-400?

The Naturalization Eligibility Worksheet is a tool that helps you determine whether you are qualified for U.S. Citizenship according to USCIS standards. 

These are the eligibility criteria for USA Naturalization with N 400 form.

  • Be at least 18 years old at the time of Form N400 application.
  • Held US Lawful Permanent Residence for at least 3 or 5 years depending on the mode of Permanent Residency application.
  • Lived continuously in the USA for at least 5 years before filing N 400 form.
  • Have not been outside the United States for 30 months or more in the past 5 years.
  • Resided in the US State where you are applying for Naturalization for a minimum of 3 months.
  • Read, speak, and write in basic English.
  • Have knowledge and understanding of US history and its government.
  • Demonstrate respect and support for the US Constitution.
  • Be a person of good moral character and be willing to take an Oath of Allegiance to the USA.

How can I Check the Status of my N-400 Application?

You are able to track the status of your N 400 Application for Naturalization through your USCIS online account. Use the 13 characters from the receipt number of your N-400 application to check your case status. You are also able to check your N400 application case status by calling the USCIS National Customer Service at 1-800-375-5283 or TTY 1-800-767-1833.

How can an Immigration Lawyer Assist with an N-400 Application?

An Immigration Lawyer helps in completing your Form N 400 correctly and ensuring you have the right evidence to support your Naturalization application. An Immigration Lawyer is an expert in US immigration and nationality laws which encompass visa, Green Card, and US Citizenship applications. You will need the help of an experienced Immigration Lawyer especially if you have potential bars to Naturalization such as criminal convictions, tax issues, and a history of long travel outside the US.

What is the Difference Between US Citizenship and Naturalization?

Naturalization is the procedure to become a US Citizen while US Citizenship is a status. You automatically gain US Citizenship if you are born in the United States or one of its territories, or if your parents are US citizens. You are eligible for US Citizenship through Naturalization if you have been an LPR for 5 years or 3 years if you are married to a US Citizen, or have served in the US military. You are given a Certificate of Naturalization after your N 400 form has been approved and you have taken the Oath of Allegiance.

What are the Differences Between Form N-400 and Form N-600?

Form N-400 is the document used to file for Naturalization to obtain USA Citizenship while Form N-600 is the document that proves you acquired US Citizenship through birth. Form N-600 is used by persons who have US Citizen parents. Form N-600 is also known as “Application for Certificate of Citizenship”. N-600 applicants are not requesting to be granted American Citizenship but a Certificate of Citizenship especially if they were born outside the United States. N-400 applicants are foreign citizens who have not been born in the US or any of its territories and have no US Citizen parents. N 400 form applicants are voluntarily requesting US Citizenship after holding Green Cards for 3 or 5 years.

Can Form N-400 be Filed Online?

Yes, you are able to file your N400 application online after creating your USCIS online account. Filing your N-400 form online gives you the ability to do the following.

  • Pay the N 400 fee online.
  • Monitor the status of your N400 application.
  • Get updates and notifications on your case.
  • Check personal case completion date estimations.
  • Respond to requests for evidence.
  • Update your contact information and address.

Is there Premium Processing for N-400?

No, premium processing is not available for Form N400 filings. Premium processing speeds up the adjudication of your application to 15 calendar days and comes with a fee. Only certain USCIS forms are eligible for premium processing such as nonimmigrant and immigrant petitions for foreign workers.