Certificate of Naturalization vs Citizenship: N-400 vs N-600

A Certificate of Naturalization and a Certificate of Citizenship both prove U.S. citizenship, but they document two different routes to it. The Certificate of Naturalization is issued to people born as foreign nationals who applied, passed the tests, and took the Oath of Allegiance as adults. The Certificate of Citizenship is issued to people who became citizens automatically through a U.S. citizen parent, either at birth abroad or during childhood. Which one you need depends entirely on how you became a citizen, not on which you’d prefer to hold.

Which Certificate Applies to You

Start with a single question: did you go through a process to become a citizen, or did the law recognize you as one without any application on your part?

If you immigrated to the United States, held a Green Card, and eventually filed Form N-400, sat for an interview, and took the oath, your document is the Certificate of Naturalization.¹

If you were born abroad to at least one U.S. citizen parent, or your parents naturalized while you were a child living lawfully in the United States, the law treated you as a citizen the moment the conditions were met. You never applied to become one. The document that records that automatic status is the Certificate of Citizenship.²

Automatic Citizenship at Birth Abroad

Children born outside the United States can be citizens from birth if a citizen parent had enough prior physical presence in the country. When both parents are citizens, at least one must have resided in the U.S. at some point. When only one parent is a citizen and the other is a foreign national, the citizen parent must have been physically present in the U.S. for at least five years, with at least two of those years after age 14.³ Different rules apply to children born out of wedlock, and the requirements have shifted over the decades depending on the year of birth and which parent is the citizen.

Automatic Citizenship in Childhood

Under the Child Citizenship Act of 2000, a child born outside the United States automatically becomes a citizen when all four conditions are met at the same time: at least one parent is a U.S. citizen by birth or naturalization, the child is under 18, the child is a lawful permanent resident, and the child lives in the U.S. in the legal and physical custody of the citizen parent.²

Adopted children fit the same framework. A child adopted abroad who enters the U.S. on an IR-3 visa typically acquires citizenship on arrival. On an IR-4 visa, citizenship follows once the adoption is completed in the United States. For families where the parent naturalized between October 1978 and February 2001, older and stricter rules can apply, often requiring both adoptive parents to have naturalized before the child turned 18.

Many people who acquired or derived citizenship this way don’t realize they are already citizens until a passport application or a job forces them to prove it. The Certificate of Citizenship exists to document that pre-existing status.

Naturalization as an Adult

The naturalization track is for adults who were born outside the United States and chose to apply. The standard requirement is age 18 or older at filing and a Green Card held for at least five years, or three years if you are married to a U.S. citizen. You also need to show physical presence for at least 30 months out of the five-year period, or 18 months out of three years for spouses of citizens.⁴⁵ Service members and veterans have separate, faster paths, and can apply with no filing fee.⁶

What Each Document Records

Both certificates are issued by USCIS and both are accepted as primary proof of citizenship. A Certificate of Naturalization lists your A-number, name, country of former nationality, certificate number, and the date of your oath ceremony, which is the date you became a citizen.¹ A Certificate of Citizenship documents a status you already held; it does not create citizenship, it records it.

Either document works as proof of citizenship for a first U.S. passport, federal employment, voter registration, and certain government benefits.⁷ A passport can stand in for the certificate in most everyday situations once you have one, but the certificate remains the underlying record of how and when you became a citizen.

How You Get Each One

The forms, fees, and steps differ substantially.

Form N-400 for Naturalization

Naturalization applicants file Form N-400. The fee is $760 by paper or $710 online.⁸ A reduced fee of $380 is available if documented household income falls below 400% of the Federal Poverty Guidelines, and a full fee waiver on Form I-912 is available at or below 150%. Neither the reduced fee nor the waiver works with an online filing; both require a paper application.⁹

After filing, you attend a biometrics appointment, then an interview where an officer reviews your case and administers the English and civics tests. The civics test for applications filed on or after October 20, 2025 draws 20 questions from a bank of 128, with 12 correct answers needed to pass. Applicants who are 65 or older with at least 20 years as a permanent resident get a shorter test and can take it in their native language.¹⁰

Approval is not the finish line. You become a citizen only when you take the Oath of Allegiance at the ceremony, and that is when USCIS hands you the Certificate of Naturalization. Check it for errors before you leave.¹¹

Form N-600 for a Certificate of Citizenship

People claiming automatic citizenship file Form N-600. The fee is $1,385 by paper or $1,335 online, higher than the naturalization fee, which surprises many applicants given that they are already citizens.⁸ The N-600 fee is waived entirely for adopted children who meet certain definitions under immigration law, and for current or former members of the U.S. armed forces.

There is no civics test, no English test, and no oath ceremony. USCIS may schedule an interview to verify identity and review documents, but the process is otherwise a paper case.¹² The real work is documentary: proving the citizen parent’s status, your relationship to that parent, and that the legal conditions were met at the relevant time. Missing records and complicated family histories are the usual sources of delay.

Processing Times

Both forms take months. N-400 processing currently runs roughly 6 to 14 months depending on the field office. N-600 falls in a similar range of about 4.5 to 14 months. After USCIS receives either application, you’ll get a Form I-797C receipt notice with a case number.¹³

Replacing or Correcting a Certificate

If either certificate is lost, stolen, or damaged, file Form N-565 for a replacement. The fee is $505 online or $555 by paper, and it is nonrefundable if USCIS cannot confirm you previously held the document. A fee waiver requires the paper version with Form I-912.¹⁴

The same form corrects errors on a certificate, such as a misspelled name or a wrong date of birth. If the error was a USCIS mistake, there is generally no charge. Replacements take time, so a valid U.S. passport is the practical bridge if you need to prove citizenship while you wait.

1
U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 12, Part K, Chapter 3 – Certificate of Naturalization
2
U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 12, Part H, Chapter 4 – Automatic Acquisition of Citizenship after Birth
3
U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 12, Part H, Chapter 3 – U.S. Citizens at Birth (INA 301 and 309)
4
U.S. Citizenship and Immigration Services. I Am a Lawful Permanent Resident of 5 Years
5
USAGov. Become a U.S. Citizen Through Naturalization
6
U.S. Citizenship and Immigration Services. Naturalization Through Military Service
7
U.S. Citizenship and Immigration Services. New U.S. Citizens
8
U.S. Citizenship and Immigration Services. G-1055 Fee Schedule
9
U.S. Citizenship and Immigration Services. Additional Information on Filing a Reduced Fee Request
10
U.S. Citizenship and Immigration Services. Study for the Test
11
U.S. Citizenship and Immigration Services. Naturalization Ceremonies
12
U.S. Citizenship and Immigration Services. Form N-600 Instructions for Application for Certificate of Citizenship
13
U.S. Citizenship and Immigration Services. Form I-797C, Notice of Action
14
U.S. Citizenship and Immigration Services. Application for Replacement Naturalization/Citizenship Document