IR2 Green Card to Citizenship: Four Conditions and Form N-400

A child who enters the United States on an IR2 immigrant visa usually becomes a U.S. citizen automatically, with no application required, the moment four conditions line up before their 18th birthday: one parent is a U.S. citizen, the child is a lawful permanent resident, the child is under 18, and the child is living in the United States in the legal and physical custody of the citizen parent. For most IR2 children this happens the day they arrive. The path from IR2 green card to citizenship only requires paperwork when a child ages out before all four conditions are met, in which case the standard five-year naturalization track applies instead.

The Four Conditions That Trigger Automatic Citizenship

The Child Citizenship Act, codified at Section 320 of the Immigration and Nationality Act, makes citizenship automatic when all of the following are true at the same time, and all before the child turns 18:¹

At least one parent is a U.S. citizen, by birth or naturalization.
The child is under 18.
The child has been lawfully admitted as a permanent resident.
The child is living in the United States in the legal and physical custody of the citizen parent.

There is no ceremony, no interview, and no approval letter. The change in legal status happens the instant the last condition clicks into place, even if no one in the family realizes it and USCIS has not been told.² For a typical IR2 child arriving to join a citizen parent already in the U.S., all four conditions are satisfied on the day of admission.

The Custody Requirement in Practice

Custody is the condition that catches the most families. USCIS looks at both legal and physical custody, and the citizen parent must have both.

Legal custody is the responsibility for and authority over a child, determined by court order or by the law of the relevant jurisdiction. Married parents living together usually share it by default. After a divorce or separation, the citizen parent needs the decree or court order showing legal custody. Where no order or statute assigns custody, USCIS treats the parent who has actual, uncontested custody as the legal custodian.³

Physical custody is read literally. The child must actually live with the citizen parent in the United States. Visits do not count, and neither does an intention to move together later.

Children Born Outside Marriage

If the U.S. citizen parent is the father and the parents were never married, the father must have legitimated the child under the law of the child’s residence or domicile before automatic citizenship can apply. Legitimation can happen through a court order or by signing an acknowledgment of paternity, depending on the jurisdiction. No legitimation step is required when the citizen parent is the mother.²

Stepchildren and Adopted Children

A stepchild can qualify for an IR2 visa and be admitted as a permanent resident, but a stepchild does not acquire automatic citizenship through the citizen stepparent. Immigration law uses a broader definition of “child” for visa eligibility than for citizenship, and stepchildren fall outside the narrower definition unless the stepparent formally adopts the child.⁴

Adopted children do qualify, but the adoption must be full and final before the child turns 18, and the child must actually reside with the adoptive citizen parent. Where an original adoption was disrupted and a new family adopted the child, the new parents generally must have adopted the child before age 16, held legal custody for at least two years, and lived with the child for two years.⁵

Proving the Citizenship You Already Have

Automatic citizenship is real from the moment the conditions are met, but proof is a separate matter. Jobs, schools, voter registration, and travel all require a document. Two options exist, and the cheaper one is often overlooked.

A U.S. passport is the most cost-effective proof. A first-time passport book costs $165 for applicants 16 and older ($130 application fee plus $35 acceptance fee), or $135 for children under 16 ($100 plus $35). The application goes to the State Department, not USCIS.⁶

A Certificate of Citizenship, obtained through Form N-600, is the formal USCIS document confirming citizenship. It is useful as a permanent record but carries a substantially higher filing fee, and Form N-600 is not eligible for a fee waiver.⁷ The N-600 instructions themselves state that obtaining evidence of citizenship is optional.⁸ In practical terms, most families need either the passport or the certificate, and the passport is usually the smarter first step.

If You Want the Certificate of Citizenship

Most applicants file Form N-600 online through a USCIS account. Paper filing is required for applicants filing from outside the United States or requesting a fee waiver for an eligible related form.⁹ The supporting documents prove each element of the automatic citizenship claim:

The child’s foreign birth certificate, with a certified English translation if needed.
Proof of permanent residence, such as the green card or admission stamp.
Proof of the parent’s U.S. citizenship: passport, U.S. birth certificate, or naturalization certificate.
Custody evidence: court orders or a divorce decree, or a marriage certificate for married parents living together.

Some cases include a biometrics appointment or an in-person interview to verify the parent-child relationship and custody. As of fiscal year 2026, the median processing time for Form N-600 is about 4.7 months, though individual cases can run longer.¹⁰

If You Turned 18 Before All Four Conditions Were Met

Automatic citizenship under the Child Citizenship Act does not apply if the child hit 18 before every condition was satisfied. A common example: the parent had not yet naturalized, or the child was still abroad. In that case, the path is standard naturalization under Section 316 of the Immigration and Nationality Act, the same route any adult permanent resident follows.¹¹

Who Can File Form N-400

Form N-400 can be filed once all of the following are true:

You are at least 18 at the time of filing.
You have five years of continuous residence as a lawful permanent resident, counted backward from the filing date. You may file up to 90 days early.¹²
You have at least 30 months of physical presence in the United States during those five years.¹³
You have shown good moral character throughout the five-year period.

The filing fee is $710 online or $760 on paper. A reduced fee of $380 is available for applicants who qualify based on income.¹²

English and Civics

The naturalization interview includes both tests. The officer assesses spoken English during the interview and asks the applicant to read one sentence aloud and write one down. The civics test covers U.S. history and government: up to 10 questions from a published study list, and at least 6 correct answers to pass.¹⁴

Selective Service for Male Applicants

Male IR2 holders between 18 and 25 must register with the Selective Service System within 30 days of turning 18 or within 30 days of entering the United States, whichever comes later. This applies to male lawful permanent residents regardless of citizenship status.¹⁵ A missed registration can derail a naturalization case. Applicants under 26 will be given a chance to register; refusal results in denial. Applicants between 26 and 31 must show the failure was not deliberate. After 31, the failure generally will not block naturalization on its own, but it can still raise questions.

The Oath

After passing the interview and exams, the last step is the oath of allegiance at a naturalization ceremony. The Certificate of Naturalization issued that day is the official proof of citizenship, and it is the document to bring when applying for a U.S. passport.

1
Office of the Law Revision Counsel. 8 USC 1431 – Children Born Outside the United States and Lawfully Admitted for Permanent Residence
2
U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 12 Part H Chapter 4 – Automatic Acquisition of Citizenship after Birth (INA 320)
3
U.S. Citizenship and Immigration Services. Custody in Acquisition of Citizenship Context
4
U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 12 Part H Chapter 2 – Definition of Child and Residence for Citizenship and Naturalization
5
U.S. Citizenship and Immigration Services. After Your Child Enters the United States
6
U.S. Department of State. United States Passport Fees for Acceptance Facilities
7
U.S. Citizenship and Immigration Services. I-912, Request for Fee Waiver
8
U.S. Citizenship and Immigration Services. Instructions for Application for Certificate of Citizenship
9
U.S. Citizenship and Immigration Services. N-600, Application for Certificate of Citizenship
10
U.S. Citizenship and Immigration Services. Historic Processing Times
11
Office of the Law Revision Counsel. 8 USC 1427 – Requirements of Naturalization
12
U.S. Citizenship and Immigration Services. N-400, Application for Naturalization
13
U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 12 Part D Chapter 4 – Physical Presence
14
eCFR. 8 CFR Part 316 – General Requirements for Naturalization
15
Selective Service System. Who Needs to Register