Difference Between Form N-400 and Form N-600 (Latest Guide)

Many immigrants are confused about Form N-400 and Form N-600 because both forms are related to U.S. citizenship. However, these two forms are used for very different purposes.

Understanding the difference is important. Filing the wrong form can lead to denial, lost fees, and long delays.

The main difference between N-400 and N-600 is this: Form N-400 is for people who want to become U.S. citizens through naturalization, while Form N-600 is for those who are already citizens but need an official certificate of citizenship. If you remember this one rule, it becomes much easier to choose the correct form.

This guide explains the difference between N-400 and N-600, when to use them, and how to use them.

What Is Form N-400 (Application for Naturalization)?

Purpose of Form N-400

Form N-400 is for people who are not U.S. citizens yet but want to become one through a process called naturalization.

You are asking the U.S. government to grant you citizenship.

Who Should File Form N-400?

You should file Form N-400 if:

• You are a green card holder (lawful permanent resident)
• You are 18 years or older
• You want to become a U.S. citizen

Key Eligibility Requirements for N-400

To qualify for naturalization, you usually must:

• Live in the U.S. for a required number of years
• Show continuous residence and physical presence (Learn the difference between continuous residence and physical presence from our guide.)
• Show good moral character
• Read, write, and speak basic English (some people are exempt)
• Pass a U.S. civics test

What Happens After Filing Form N-400?

After you file Form N-400, USCIS usually follows these steps:

1. Biometrics appointment – USCIS collects your fingerprints, photo, and signature to verify your identity and complete background checks. Learn more about what happens at the biometrics appointment and how to prepare.
2. Citizenship interview – A USCIS officer reviews your application, asks eligibility questions, and confirms your readiness for U.S. citizenship. Read our complete guide to the U.S. citizenship interview.
3. English and civics test – Most applicants must show basic English skills and answer questions about U.S. history and government. See what questions are asked on the English and civics test and how to prepare.
4. Oath of Allegiance ceremony – You officially become a U.S. citizen by taking the Oath of Allegiance and receiving your Certificate of Naturalization.

What Do You Receive After N-400 Approval?

After approval and the oath ceremony, you receive a:

• Certificate of Naturalization

You officially become a U.S. citizen on the oath date.

What Is Form N-600 (Application for Certificate of Citizenship)?

Purpose of Form N-600

Form N-600 is not used to become a U.S. citizen.

It is used to request proof that you already became a U.S. citizen automatically under U.S. law.

Who Should File Form N-600?

You should file Form N-600 if:

• You became a U.S. citizen through a parent
• You were born outside the U.S. to U.S. citizen parent(s)
• You already have citizenship but need official proof

Common Situations Where Form N-600 Is Needed

Form N-600 is often used when:

• A parent became a U.S. citizen while the child was under 18
• A child entered the U.S. as a permanent resident and lived with a U.S. citizen parent
• A U.S. passport application requires additional proof
• A government agency or employer asks for a Certificate of Citizenship

Eligibility Rules for Derived Citizenship (Simple Explanation)

In many cases, a child automatically becomes a U.S. citizen if:

• At least one parent is a U.S. citizen
• The child is under 18 years old
• The child lives in the U.S. as a permanent resident
• The child is in the legal and physical custody of the U.S. citizen parent

What Happens After Filing Form N-600?

After filing Form N-600:

• USCIS reviews your documents
• No English test
• No civics test
• Usually no interview

What Do You Receive After N-600 Approval?

If approved, USCIS issues a:

• Certificate of Citizenship

This certificate confirms that you became a citizen earlier, not on the approval date.

Key Differences Between N-400 and N-600 (Explained Clearly)

To help you decide which form is right for your situation, here are the main differences between N-400 and N-600:

Category	Form N-400	Form N-600
Citizenship Status	You are not yet a U.S. citizen	You are already a U.S. citizen
Type of Application	Application to become a U.S. citizen	Application for proof of U.S. citizenship
Who Should Apply	Green card holders seeking citizenship	People who gained citizenship automatically
Interview Required	Yes	Usually no
English & Civics Test	Yes	No
Residency Requirement	Required	Not required
Good Moral Character	Required	Not required
Final Outcome	Citizenship is granted	Citizenship is confirmed
Certificate Issued	Certificate of Naturalization	Certificate of Citizenship

Is a U.S. Passport the Same as a Certificate of Citizenship?

When a Passport Is Enough

A U.S. passport is usually enough for:

• Travel
• General proof of U.S. citizenship

When a Certificate of Citizenship Is Needed

Some situations require a Certificate of Citizenship:

• Certain government benefits
• Employment verification
• Replacing a lost passport
• Legal certainty for life

A passport can expire. A Certificate of Citizenship does not.

Can You File Form N-400 and Form N-600 at the Same Time?

No.

You must choose only one form based on your situation. Filing both can cause:

• Confusion
• Delays
• Denial of one or both applications

Fees and Processing for N-400 and N-600

Filing fees for these forms are expensive, so it’s important to understand the costs involved before applying. In 2026, the filing fee for Form N-400 is $760 (paper filing), and $710 (online filing).

For most applicants, the Form N-600 fee comes with a $1,385 (paper filing) and $1,335 (online filing).

Note: Before filing your application, cross-check and make sure the USCIS fee matches the application fee you are paying. Most USCIS fees are non-refundable, even if your application is denied, so be sure you are using the correct form before you file.

Documentation and Proof Requirements

When you file Form N-400, you’ll need to provide various documents such as your green card (Form I-551), evidence of marital status if applying under the 3-year rule, and records of any criminal history or legal issues. These documents help prove your eligibility for naturalization.

For Form N-600, you will need to submit documents that prove your claim to citizenship. Typical proof includes your birth certificate, your parents’ citizenship documents, and evidence of your parents’ physical presence in the U.S. before your birth. Providing accurate and complete documentation is important for both forms, as missing or incorrect paperwork can delay your application or lead to denial.

Need Help Applying for Citizenship or Requesting Your Certificate?

Understanding the difference between Form N-400 and Form N-600 is very important before applying for U.S. citizenship or requesting proof of citizenship. Filing the wrong form can lead to delays, denied applications, and lost filing fees. If you are applying to become a U.S. citizen, Form N-400 is the correct choice. If you are already a U.S. citizen and need official proof, Form N-600 is the right option.

Don’t risk filing the wrong form and losing your application fee. Consider speaking with an immigration professional who can review your situation, confirm the correct form, and guide you through the filing process step by step—so you can move forward with confidence.