Certificate of Citizenship Basics: What USCIS Says About Form N-600 for Children of U.S. Citizens

By Pacheco Couceiro

In Brownsville and the Rio Grande Valley, many families include children who were born in Mexico or another country and later came to live in the United States with a parent who is, or became, a U.S. citizen. Some of those children may already be U.S. citizens under federal law without ever filing a naturalization application. USCIS explains that a person in that situation can ask for official proof by filing Form N-600, Application for Certificate of Citizenship. This article summarizes what USCIS publishes about INA 320 and the N-600 process. Sources were checked on November 10, 2026, and federal procedures can change. This article does not evaluate any person's citizenship claim or predict any outcome.

Acquiring citizenship versus applying for naturalization

Naturalization is the process an adult permanent resident uses to apply to become a citizen, usually with Form N-400. A Certificate of Citizenship is different: it documents citizenship that a person already acquired through a U.S. citizen parent, either at birth or automatically after birth.

The USCIS Policy Manual, Volume 12, Part H, Chapter 4 explains that the Child Citizenship Act of 2000 created one statutory method, INA 320, for children in the United States to automatically acquire citizenship after birth. People who may have been citizens at birth because they were born abroad to a U.S. citizen parent are covered in Chapter 3 of the same Part. This article does not cover those rules.

The four INA 320 conditions

According to Chapter 4, a child born outside the United States automatically becomes a U.S. citizen when all of these conditions are met on or after February 27, 2001:

The child has at least one parent who is a U.S. citizen by birth or through naturalization (including an adoptive parent)
The child is under 18 years of age
The child is a lawful permanent resident (LPR)
The child is residing in the United States in the legal and physical custody of the U.S. citizen parent

USCIS states there is no required order: all conditions must be met at a single point in time before the child's 18th birthday. The Policy Manual also notes that a person born outside the United States is presumed to be an alien and that the person claiming citizenship has the burden to establish, by a preponderance of the evidence, that all requirements were met.

Legal and physical custody

Custody questions come up often in families with divorced, separated, or never-married parents. Chapter 4 explains, in summary:

Married parents: unless there is evidence to the contrary, USCIS presumes a U.S. citizen parent has legal custody of a biological child who lives with married parents in marital union.
Never-married parents: USCIS generally considers the parent the child lives with to have legal custody; if that parent is a U.S. citizen father, he must also have legitimated the child.
Divorce or legal separation: USCIS looks to the court order. The U.S. citizen parent has legal custody for INA 320 purposes when a court awarded that parent primary care, control, and maintenance of the child. Joint custody orders generally count for both parents.
Private agreements: a private custody agreement between parents generally does not change a court's custody determination.
Late court orders: USCIS does not recognize nunc pro tunc custody orders entered after the child's 18th birthday that change custody retroactively.

Physical custody means actual residence with the U.S. citizen parent. The Policy Manual lists evidence that may show it, such as matching addresses on school, medical, or vaccination records, the parent's federal income tax transcripts listing the child as a dependent, or notarized affidavits from either parent describing when the child lived with the U.S. citizen parent.

Who files Form N-600

Chapter 4 says a person who automatically acquired citizenship is not required to have evidence of that status, but may file Form N-600 to get documentation. A person who is at least 18 may file on their own behalf. For a child under 18, a U.S. citizen parent or legal guardian must file. A U.S. passport from the Department of State is another form of evidence of citizenship; USCIS notes that a passport is valid for a limited time, while a Certificate of Citizenship does not expire.

For children who regularly reside outside the United States, USCIS points to a different form, Form N-600K, which is based on INA 322.

How to file

The N-600 page says you can file online or by mail. You cannot currently file online if you are applying from outside the United States, are requesting a fee waiver, or are a member or veteran of the U.S. military filing on your own behalf. To file online you must create a USCIS online account, which also lets you pay the fee, check case status, and respond to requests for evidence.

For paper filing, the N-600 page lists the lockbox address by state; Texas filers are directed to the Phoenix Lockbox. USCIS publishes the current fee on its Fee Schedule page. The N-600 page also notes that applicants residing in the United States generally do not send photos; USCIS schedules an appointment at a local Application Support Center to take them.

USCIS lists filing tips: check only one box in Part 1, Question 1 and only one in Part 1, Question 2; complete the required fields in Part 2; and sign the form. USCIS says it will reject unsigned forms. A parent or legal guardian signs for a child under 14.

Evidence USCIS lists

The Policy Manual lists required documents, when they apply and are not already in the USCIS record, including:

The child's birth certificate or record
The parents' marriage certificate, if applicable, and proof that any prior marriage of either parent ended
Evidence of the parent's U.S. citizenship, such as a birth certificate, naturalization certificate, Consular Report of Birth Abroad, valid U.S. passport, or Certificate of Citizenship
Documents showing legitimation, if the child was born out of wedlock and the claim is through the father
Documents showing legal custody in cases of divorce, legal separation, or adoption
Evidence that the child resided in the United States in the U.S. citizen parent's physical custody while under 18
A copy of the child's Permanent Resident Card or other evidence of LPR status
Evidence of any legal name changes

USCIS requires a full English translation, with the translator's certification, for documents in Spanish or another foreign language.

Interview, oath, and decision

Chapter 4 says an applicant generally must appear for an interview, including the U.S. citizen parent when the application is for a child under 18. USCIS may waive the interview when the record already establishes eligibility.

If the application is approved, USCIS administers the Oath of Allegiance before issuing the certificate, but waives the oath for children under 14. If USCIS denies the application, the Policy Manual says the written decision explains the reasons and appeal rights, and an appeal may be filed within 30 calendar days after service of the decision (33 days if the decision was mailed).

Step by step: preparing an N-600 filing

1. Map the timeline

Write down the dates the child became a permanent resident, began living with the U.S. citizen parent, and when the parent became a citizen, and compare them with the child's 18th birthday.

2. Collect civil records

Gather birth and marriage certificates, divorce decrees, and any custody orders, with certified English translations.

3. Collect residence evidence

Pull school, medical, and tax records that show the child living with the U.S. citizen parent before age 18.

4. Choose online or paper filing

Confirm whether online filing is available for your situation, check the current form edition and fee, and keep copies.

5. Watch for notices

Attend the biometrics appointment and interview, and answer any request for evidence by the deadline.

Frequently asked questions

Is the Certificate of Citizenship the same as naturalization?

No. Chapter 4 describes INA 320 citizenship as automatic when all conditions are met. The N-600 documents that status; it does not create it.

My child is over 18. Is it too late?

The conditions must have been met before age 18, but USCIS says a person 18 or older may file Form N-600 on their own behalf to document citizenship acquired earlier.

Where can I find legitimate help?

USCIS lists options on its Find Legal Services page.

Questions in Brownsville and the Rio Grande Valley

Pacheco Couceiro assists families in Brownsville and South Texas with immigration matters. If you want to understand how the INA 320 conditions and the Form N-600 evidence list apply to your family's documents, you can contact the office to review those records.

This article is general information, not legal advice. Reading it or contacting the office does not create an attorney-client relationship.

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