Form N-400 Guide: Application for Naturalization

What Is Form N-400?

Form N-400, Application for Naturalization, is the USCIS form used to apply for U.S. citizenship through naturalization. Many applicants apply under the general five-year lawful permanent resident rule.

Certain spouses of U.S. citizens may qualify after three years, while different rules apply to some military members and other applicants.

USCIS uses Form N-400 to review your eligibility for naturalization. The form asks about your immigration history, residence, travel, family, employment, and background. Filing Form N-400 does not make you a U.S. citizen by itself.

If USCIS approves your application, you must complete the naturalization process and take the Oath of Allegiance before becoming a U.S. citizen.

Form N-400 at a glance:

• Official name: Application for Naturalization
• Agency: U.S. Citizenship and Immigration Services (USCIS)
• Purpose: Apply for U.S. citizenship through naturalization
• Current form edition: 01/20/25
• Filing options: Online or by mail, depending on your filing circumstances
• Standard USCIS filing fee: $710 online or $760 by mail

This guide explains who can file Form N-400, when to apply, what information and documents you may need, how and where to file, and what happens after USCIS receives your application.

Who Can File Form N-400?

In general, you can file Form N-400 if you are at least 18 years old and meet the naturalization requirements that apply to your situation. Many applicants qualify under the general five-year permanent resident rule, while certain spouses of U.S. citizens may qualify under a three-year rule.

Five-Year Permanent Resident Rule

Under the general rule, you must have been a lawful permanent resident for at least five years before naturalizing. You generally must also:

• Maintain continuous residence in the United States for the required five-year period.
• Be physically present in the United States for at least 30 months during those five years.
• Live for at least three months in the state or USCIS district where you file.
• Show good moral character.
• Meet the English and civics requirements unless you qualify for an exception.
• Show attachment to the principles of the U.S. Constitution and be willing to take the Oath of Allegiance.

Three-Year Rule for Certain Spouses of U.S. Citizens

Some permanent residents may qualify after three years if they are married to a U.S. citizen and meet the additional marriage requirements. They generally need three years of continuous residence, at least 18 months of physical presence, and three months of residence in the state or USCIS district where they file.

Different requirements can apply to military members and applicants using other naturalization provisions. See our U.S. citizenship eligibility requirements guide for the complete eligibility rules and exceptions.

When Can You File Form N-400?

You can file Form N-400 once you meet the naturalization requirements for your eligibility category. If you qualify under the standard five-year permanent resident rule or the three-year rule for certain spouses of U.S. citizens, you may be able to file before completing the full continuous-residence period.

The 90-Day Early Filing Rule

USCIS allows eligible applicants under these two categories to file Form N-400 up to 90 calendar days before completing the required five-year or three-year period of continuous residence.

Early filing applies only to the continuous-residence requirement. You must still meet the other naturalization requirements that apply to you when you file. For example, an applicant using the three-year rule must already meet the applicable marriage requirements when Form N-400 is submitted.

USCIS may deny Form N-400 if you file more than 90 calendar days before completing the required continuous-residence period. Before filing, use the USCIS Early Filing Calculator to determine the earliest date you may submit Form N-400.

Who May Not Need Form N-400?

You may not need Form N-400 if you are already a U.S. citizen through a U.S. citizen parent. Some people born outside the United States acquire citizenship at birth, while others automatically acquire citizenship after birth when the applicable requirements are met.

If you already acquired U.S. citizenship, Form N-400 is not used to naturalize you. Depending on your circumstances, you may be able to apply for a U.S. passport or file Form N-600 to obtain a Certificate of Citizenship as evidence of your citizenship.

Citizenship through a parent depends on several factors, including when you were born and which citizenship law applied at the time. See our Form N-600 eligibility requirements guide if you believe you may already be a U.S. citizen.

Form N-400 Instructions: What Information Does the Form Ask For?

Form N-400 asks for information USCIS uses to determine whether you qualify for naturalization. Before you start, gather records covering your immigration history, addresses, work or school history, travel, and family information so you can answer the form accurately.

Information You Will Need to Provide

The Form N-400 instructions require information about several areas of your history and eligibility. Depending on your naturalization category and circumstances, the form asks for:

• Your basis for applying for naturalization.
• Your legal name, other names used, date of birth, and immigration information.
• Your current and previous addresses for the required period.
• Your employment, education, unemployment, or other activity history.
• Trips you have taken outside the United States.
• Your marital history and information about your spouse, when applicable.
• Information about your children.
• Background questions related to taxes, criminal history, immigration history, organizations, military service, and good moral character.
• Information about an interpreter or preparer, if you used one.

You must also provide the required certifications and signatures.

Review Your Answers Before Filing

Review the completed form against your records before you submit it. Make sure names, dates, addresses, trips, and other information are complete and consistent.

Pay particular attention to questions that ask whether something has ever happened, because those questions may cover events outside the normal three- or five-year eligibility period.

For a detailed explanation of each part of the application, see our step-by-step Form N-400 instructions.

What Documents Do You Need for Form N-400?

The documents you need with Form N-400 depend on your eligibility category and personal history. Not every applicant submits the same evidence.

Depending on your situation, you may need:

• Evidence of lawful permanent resident status, including your Permanent Resident Card where applicable.
• Documents supporting the naturalization category under which you are filing.
• Marriage certificates, divorce decrees, or other marriage records.
• Evidence related to extended trips outside the United States.
• Tax records when required by your circumstances.
• Court or law-enforcement records for certain arrests, charges, or convictions.
• Selective Service or military records when applicable.
• Form N-648 if you are requesting a medical disability exception from the English or civics requirements.

Some documents may be needed only for a particular issue or eligibility category. See our complete Form N-400 document checklist before filing.

How Much Does Form N-400 Cost?

The standard USCIS filing fee for Form N-400 is $710 when filed online or $760 when filed on paper. USCIS does not charge a separate biometric services fee for Form N-400.

Some applicants may qualify for a $380 reduced filing fee. Others may qualify for a complete fee waiver. Applicants filing for naturalization based on qualifying military service under INA sections 328 or 329 do not pay an N-400 filing fee.

Applicants requesting a reduced fee or fee waiver must file Form N-400 on paper rather than online.

USCIS fees and filing rules can change. See our U.S. citizenship cost and N-400 fee guide for current fees, reduced-fee rules, fee waivers, and payment information.

How Can You File Form N-400?

Form N-400 can generally be filed online or by mail. The correct method depends on your filing circumstances and whether you are requesting a reduced fee or fee waiver.

File Form N-400 Online

Eligible applicants can create a USCIS online account, complete Form N-400 electronically, upload supporting evidence, pay the filing fee, and submit the application online.

You cannot file Form N-400 online if you are requesting a reduced filing fee or a fee waiver. Those requests must be submitted with a paper application.

File Form N-400 by Mail

If you file on paper, use the current edition of Form N-400 accepted by USCIS and follow the current filing instructions. Complete and sign the form, include the required supporting evidence, and use the filing method that applies to your case.

Before submitting either version, keep a complete copy of your Form N-400 and the evidence you provided. You may need to review your answers again before your naturalization interview.

Where Do You File Form N-400?

Where you file Form N-400 depends first on whether you submit the application online or by mail. Online applicants file through USCIS electronically, while paper applicants must send their application to the USCIS address that applies to their filing circumstances.

Filing Form N-400 Online

If you are eligible to file online, submit Form N-400 through your USCIS online account. You do not need to send the same application separately to a USCIS mailing address.

Mailing Form N-400

There is not one N-400 mailing address that applies to every paper applicant. The correct USCIS filing address may depend on where you live, your eligibility or filing category, and the delivery service you use.

Certain applicants, including some military applicants or people filing under special naturalization provisions, may have different filing instructions.

Before mailing Form N-400, check the current USCIS Form N-400 filing addresses and follow the instructions for your situation. Confirm the address shortly before you send the application, because USCIS can update Lockbox locations and filing instructions.

Using an outdated or incorrect N-400 filing address can result in the package being returned or delay USCIS in accepting the application.

What Happens After You File Form N-400?

After USCIS accepts your Form N-400, your case moves through several steps before you can become a U.S. citizen. The exact sequence can vary, but most applicants can expect the following process:

1. Receipt notice and case tracking: USCIS sends a receipt notice with a receipt number you can use to check your case status.
2. Biometrics, if required: USCIS will notify you about any required biometrics appointment and provide instructions for identity verification and background checks.
3. Naturalization interview: USCIS schedules a naturalization interview where an officer reviews your Form N-400, supporting information, and eligibility for naturalization.
4. English and civics tests: Unless you qualify for an exception or accommodation, you will take the required English and civics tests during the naturalization process. When you are ready to study, review our citizenship test questions and answers.
5. USCIS decision: After reviewing your case, USCIS issues a decision on your Form N-400. In some cases, USCIS may request additional information before making a final decision.
6. Oath ceremony: If your application is approved, USCIS schedules you to attend the Oath of Allegiance ceremony, where you take the oath required to become a U.S. citizen.
7. Certificate of Naturalization: You become a U.S. citizen after taking the Oath and receive your Certificate of Naturalization as evidence of your citizenship.

For a broader explanation of these stages, see our naturalization process guide.

How Long Does Form N-400 Take?

There is no single processing time for every Form N-400 application. How long your case takes can depend on the USCIS field office handling it and the circumstances of your case.

Requests for additional evidence, rescheduled appointments, background or security checks, and other case-specific issues can also affect the timeline. USCIS processing times change, so a timeframe that applied to another applicant may not apply to your case.

See our current N-400 processing times guide for the latest USCIS data and field-office information.

Can USCIS Deny Form N-400?

Yes. USCIS can deny Form N-400 if it determines that you have not established eligibility for naturalization.

Reasons can include not meeting the applicable continuous-residence or physical-presence requirements, not establishing good moral character, or not meeting the required English and civics requirements when no exception applies. Material false statements or omissions can also affect eligibility.

USCIS may also deny an application when required evidence does not establish that the applicant meets the applicable naturalization requirements.

Having a particular issue in your history does not automatically mean your application will be denied. See our guide to reasons Form N-400 may be denied for a more detailed explanation.

Form N-400 FAQs