What Is a Derived U.S. Citizen? Conditions, Proof, and Form N-600

A derived U.S. citizen is a child who automatically became a U.S. citizen because a parent was or became a citizen while the child was under 18, living in the United States as a lawful permanent resident, and in that parent’s legal and physical custody. No application, test, or oath is required for the citizenship itself. What most people need is proof it happened, either a Certificate of Citizenship or a U.S. passport, and the rules that govern eligibility depend on when the child turned 18.

The Three Conditions Under Current Law

Section 320 of the Immigration and Nationality Act, codified at 8 U.S.C. § 1431, sets the rule that applies to anyone who was still under 18 on February 27, 2001, or born after that date. All three of the following must be true at the same moment for citizenship to transfer automatically:

At least one parent is a U.S. citizen, by birth or through naturalization. If the parent naturalizes, the child’s citizenship takes effect at the moment of the oath, provided the other two conditions are already in place.¹
The child is under 18. Once the child turns 18 without every condition being met, this door closes permanently.²
The child is residing in the United States as a lawful permanent resident, in the legal and physical custody of the citizen parent. That means a green card, actually living with the parent, and the parent holding legal authority over the child.¹

The parent doesn’t have to have naturalized. If a U.S.-born citizen parent brings a child born abroad to the United States as a permanent resident and the child lives with that parent while under 18, the child can derive citizenship without anyone going through naturalization.

When Legal Custody Gets Complicated

The custody piece is where most families run into trouble. “Legal and physical custody” means the citizen parent lives with the child and has legal authority over them. Married, cohabiting parents satisfy this without effort. Everything else takes documentation.

For divorced or legally separated parents, custody is determined by the court order or by the law of the state or country where the family lives. Sole custody to the citizen parent settles the question. Joint custody arrangements can also work, as long as the citizen parent has legal authority. In November 2024, USCIS clarified that when no court has ruled on custody and the jurisdiction’s law does not assign custody to a specific parent, the citizen parent who has actual uncontested custody is treated as having legal custody for citizenship purposes.³

For children born outside of marriage, the regulations presume the citizen parent has legal custody if the child has been legitimated under applicable law and currently lives with that parent.² A citizen father typically needs legitimation documents under the law of the child’s home country or his own. A citizen mother establishes the relationship through the birth certificate, though additional custody documents may still be needed if the parents never married.

Adopted Children

Adopted children can derive citizenship under Section 320, but they must first qualify as a “child” under the immigration statute’s own definition, which imposes an age cap on the adoption itself. Generally, the adoption must have been finalized before the child turned 16.⁴ A sibling exception allows adoption up to age 18 if the child was adopted alongside or after a sibling who met the standard rule.

For international adoptions, the full and final adoption decree from the foreign country must be provided. If the foreign adoption was not full and final, which is common when a child enters on an IR-4 visa to be adopted in the United States, the adoptive parents need either a domestic adoption decree or evidence that the state where the child lives recognizes the foreign adoption.² Until the adoption is legally final, the child cannot derive citizenship even if every other condition is met.

Military and Government Families Stationed Abroad

Ordinarily the child must be residing in the United States. Congress carved out an exception for families serving overseas. A lawful permanent resident child is treated as residing in the United States if the citizen parent is stationed abroad as a member of the Armed Forces or as a federal government employee, and the child is living with that parent. The same rule applies if the citizen parent is the spouse of the service member or employee and is authorized to accompany them abroad.¹

So a child living on a base in Germany with a naturalized citizen parent can derive citizenship without the family first returning to U.S. soil. The child still needs a green card and must be under 18.

If You Turned 18 Before February 27, 2001

The Child Citizenship Act of 2000 only helps people who were still under 18 on its effective date. Anyone older on that date is evaluated under the former Section 321 of the Immigration and Nationality Act, which was significantly stricter.⁵

The general rule under the old law required both parents to naturalize, not just one. Exceptions applied: if one parent had died, only the surviving parent needed to naturalize; if the parents were divorced or legally separated, only the parent with legal custody needed to; and for a child born outside marriage whose paternity was never established through legitimation, only the mother’s naturalization counted. The child had to be under 18 at the time of the qualifying naturalization and had to be a lawful permanent resident either then or before turning 18.

This catches out some people in their 40s and older who grew up assuming they became citizens through a parent’s naturalization but whose family circumstances didn’t satisfy the two-parent requirement. The analysis is fact-intensive, and getting it wrong has real consequences, so it is often worth reviewing with an immigration attorney.

Why You Still Need to Prove It

Automatic citizenship isn’t documented citizenship. Without proof, you can’t get a U.S. passport, and you can hit walls with employment verification, federal financial aid, and other situations where citizenship must be shown. In the worst case, a derived citizen without documentation can end up in removal proceedings, forced to establish citizenship defensively in immigration court instead of with a routine document.

There are two main ways to prove it, and you don’t necessarily need both.

Certificate of Citizenship (Form N-600)

The Certificate of Citizenship is the most definitive proof. You obtain it by filing Form N-600 with USCIS. This is not an application to become a citizen; it is a request for USCIS to confirm that you already are one. The certificate is a standalone document you can use to apply for a passport, update your Social Security record, or establish status for any other purpose.

The filing fee is $1,385 for a paper submission or $1,335 online.⁶ There is no separate biometrics fee, though USCIS may require a biometrics appointment to verify identity and run background checks.⁷ Processing times vary by field office and can stretch beyond a year, so filing early matters if you have upcoming travel or employment needs.

U.S. Passport

If you don’t already have a Certificate of Citizenship, you can apply for a U.S. passport directly, submitting evidence of your derived citizenship to the State Department. Expect to provide your foreign birth certificate, your parent’s proof of citizenship (such as a naturalization certificate), your green card or other evidence of permanent resident status, and documents showing you lived with your citizen parent, such as school records, medical records, or utility bills.⁸ If your parents weren’t married when you entered the country, you’ll also need documentation of legal custody and, if applicable, legitimation.

The passport route is cheaper and often faster than the N-600 process, but a passport expires and doesn’t function as permanent proof of citizenship. Many people apply for the passport first and file the N-600 later, or skip the certificate entirely if a passport is all they need.

Documents to Gather

Pulling the records together is usually the hardest part of either process. For an N-600, expect to provide:

Your birth certificate: an original or certified copy from the country of birth, showing both parents’ names.
Your parent’s proof of U.S. citizenship: naturalization certificate, U.S. birth certificate, or U.S. passport.
Your green card or other proof of permanent resident status: a copy of your Permanent Resident Card or the original I-551 stamp in your passport.
Parents’ marriage certificate, if applicable, to establish the parent-child relationship.
Custody documentation: divorce decrees, legal separation orders, or court-ordered custody arrangements if the parents weren’t married or living together.
Adoption decree, if you were adopted, plus any state recognition of a foreign adoption where needed.
Legitimation documents if you were born outside of marriage.

Any originals in a foreign language must come with certified English translations.⁷

Fee Waivers

The N-600 fee is steep, but USCIS accepts fee waiver requests on Form I-912. You can qualify in two main ways. First, if you, your spouse, or a parent or sibling in your household currently receives a means-tested government benefit such as Medicaid, SNAP, or Supplemental Security Income, submit recent proof of that benefit.⁹ Second, if your household’s adjusted gross income is at or below 150 percent of the Federal Poverty Guidelines for your household size, submit tax returns or pay stubs as evidence.¹⁰ USCIS looks at income at the time of the request, not historically, so a recent job loss or change in circumstances can make someone newly eligible.

After You Have Proof

Once you hold the certificate or passport, take care of two follow-ups.

Update your Social Security record. It may still list your previous immigration status. Apply for a replacement Social Security card through the SSA, bringing proof of identity and your new citizenship status; a replacement typically arrives by mail within five to ten business days.¹¹ This matters for employment verification and future benefit eligibility.

If you’re male and between 18 and 25, register with the Selective Service System. Male U.S. citizens in that age range are required to register, and if you derived citizenship between 18 and 25, you must register within 30 days.¹² Failing to register can affect eligibility for federal student aid, federal job training programs, and federal employment.

1
Office of the Law Revision Counsel. 8 USC 1431 – Children Born Outside the United States and Lawfully Admitted for Permanent Residence
2
eCFR. 8 CFR Part 320 – Child Born Outside the United States and Residing Permanently in the United States
3
U.S. Citizenship and Immigration Services. Policy Alert – Custody in Acquisition of Citizenship Context
4
Office of the Law Revision Counsel. 8 USC 1101 – Definitions
5
U.S. Citizenship and Immigration Services. Chapter 7 – Deriving Citizenship Before the Child Citizenship Act of 2000
6
U.S. Citizenship and Immigration Services. G-1055, Fee Schedule
7
U.S. Citizenship and Immigration Services. N-600, Instructions for Application for Certificate of Citizenship
8
Travel.State.Gov. Get Citizenship Evidence for a U.S. Passport
9
U.S. Citizenship and Immigration Services. I-912, Request for Fee Waiver
10
U.S. Citizenship and Immigration Services. Chapter 4 – Fee Waivers and Fee Exemptions
11
Social Security Administration. Update Citizenship or Immigration Status
12
Selective Service System. Who Needs to Register