Derivative Citizenship for Adults: INA 320, 321, and Form N-600

If you’re an adult wondering about derivative citizenship, the first thing to understand is that you don’t apply for it. U.S. law confers citizenship automatically on certain children of citizen parents the moment all the required conditions are met. If that happened to you before your 18th birthday, you’ve been a U.S. citizen ever since, whether or not anyone told you. What adults in this position actually need is documentation, usually a Certificate of Citizenship from USCIS or a U.S. passport.

USCIS states the point directly: a person who automatically acquires citizenship “is not required to have evidence of such status.”¹ The Certificate of Citizenship issued through Form N-600 is proof of something that already happened. It doesn’t make you a citizen; it confirms you already are one.

That distinction has real consequences. If you were denied a benefit, detained, or removed because no one recognized your citizenship, you may have legal recourse. And if you’ve spent your adult life abroad without realizing you were a U.S. citizen, the IRS has been expecting tax filings from you the whole time.

Which Law Applies Depends on Your Age on February 27, 2001

The Child Citizenship Act of 2000 took effect on February 27, 2001, and it split the eligibility rules in two.¹

If you were still under 18 on February 27, 2001, the current law (INA 320) applies.
If you had already turned 18 before that date, the former law (INA 321) applies.

Either way, every condition had to be satisfied before you turned 18. If even one piece fell into place after your 18th birthday, derivative citizenship did not occur, and you would need a different path to citizenship if you want it now.

Eligibility Under Current Law (INA 320)

If you were under 18 on February 27, 2001, you automatically became a citizen when all three of these conditions were true at the same time:²

At least one of your parents was a U.S. citizen, by birth or naturalization, including an adoptive parent.
You were under 18.
You were living in the United States as a lawful permanent resident (green card holder) in the legal and physical custody of your citizen parent.

That third condition packs a lot in. You needed a green card. You needed to actually live in the U.S., not just visit. And you needed to be in your citizen parent’s custody. If your parents were divorced, legal custody usually turns on a court order. USCIS defines legal custody as “the responsibility for and authority over a child” as determined by the relevant jurisdiction’s law or a court decree.³

Eligibility Under Former Law (INA 321)

If you turned 18 before February 27, 2001, the stricter former rules govern your case. Under INA 321, you derived citizenship if one of the following happened before your 18th birthday:³

Both parents naturalized, or
One surviving parent naturalized after the other parent died, or
The parent with legal custody naturalized after the parents divorced or legally separated, or
Your mother naturalized, if you were born outside of marriage and paternity was never legally established.

On top of whichever parent condition applied, you also had to be a lawful permanent resident and under 18 when the naturalizing event happened. Your parents’ marital status both at your birth and at the time of naturalization can matter to the analysis. If you were born before December 24, 1952, even older laws may apply, and that situation is unusual enough that an immigration attorney is worth consulting.

If You Grew Up Outside the United States

A separate provision, INA 322, lets a U.S. citizen parent apply for citizenship for a child living abroad, but this route is not automatic. The parent had to file the application, and the child had to enter the United States and take the Oath of Allegiance while still under 18.⁴ If that didn’t happen before your 18th birthday, this path is closed to you now. Adults who grew up abroad and believe they should have citizenship through a parent will almost always need to look at INA 320 or the former INA 321 instead.

How to Prove You’re Already a Citizen

Two documents are commonly used to establish derivative citizenship, and many people pursue both.

The Certificate of Citizenship is issued by USCIS through Form N-600, Application for Certificate of Citizenship. It is a permanent record that doesn’t expire. USCIS adjusts filing fees annually, so check the current fee schedule before filing.⁵ You can file online, or by mail if you’re requesting a fee waiver.⁶

A U.S. passport is often faster and cheaper to obtain, and the State Department accepts direct passport applications from people who derived citizenship through a parent, provided you submit the same underlying evidence.⁷ A passport works as proof of citizenship for most purposes, but it expires. The Certificate of Citizenship is useful as a permanent backup and in immigration proceedings where a passport alone might not carry the day.

Evidence You’ll Need to Gather

Because you’re proving something that already occurred, the task is essentially reconstructing a timeline showing every required condition was met before you turned 18. Plan to assemble:

Your foreign birth certificate listing your parents.
Proof of your parent’s U.S. citizenship: birth certificate, Certificate of Naturalization, or Consular Report of Birth Abroad.
Evidence of your green card status: your Permanent Resident Card, I-551 stamp in your passport, or other proof of lawful permanent residence before age 18.
Your parents’ marriage certificate, and, if either parent had a prior marriage, proof that the earlier marriage ended.
Custody documentation if your parents were divorced or separated, such as a court order showing which parent had legal custody.
Proof you lived in the United States with your citizen parent: school records, medical records, utility bills, or similar documents.

The State Department’s guidance on citizenship evidence flags a frequent stumbling block: entering the country or visiting temporarily, even on an immigrant visa, generally doesn’t count as residing there.⁷ You need evidence of an actual home in the United States with your citizen parent. A green card alone doesn’t prove residence.

Certified copies of birth and marriage records from state vital records offices typically cost between $16 and $45 each. Order extras, because USCIS requires originals or certified copies, not photocopies.

Filling Out Form N-600

Part 1 of the form asks you to identify the specific legal provision you qualify under: INA 320 for most people who were under 18 on February 27, 2001, or former INA 321 for those who turned 18 before that date. Part 2 covers your personal details and immigration history. Part 3 asks for your citizen parent’s information and naturalization details if applicable. Match every entry to your supporting documents exactly. Small discrepancies between the form and your certificates are a common cause of delays and evidence requests.

After You File

USCIS will send a receipt notice (Form I-797C) with a case number you can use to check status online.⁸ As of early 2026, N-600 processing time runs roughly 4.7 months, though individual cases can take longer depending on the field office and the complexity of the evidence.

Biometrics and interviews are not automatic. USCIS will send a notice if a biometrics appointment is needed,⁹ and it decides based on the evidence whether an in-person interview is required. If your application is approved and you are over 14, USCIS will schedule you to take the Oath of Allegiance before issuing the certificate. Applicants under 14 may not be required to take it.¹⁰ It can feel odd to take an oath for a citizenship you already have, but USCIS treats it as part of issuing the certificate.¹

If Your Application Is Denied

A denial doesn’t mean you aren’t a citizen. It means USCIS wasn’t persuaded by what you submitted. You can appeal or file a motion to reopen or reconsider, using Form I-290B. You have 30 calendar days from the date USCIS issued the decision to file, or 33 days if the decision was mailed.¹¹ The “date of service” is the day USCIS mailed the decision, not the day it reached you. Miss the deadline and the appeal will be rejected, though USCIS may treat a late appeal as a motion to reopen if it meets the requirements.¹²

An appeal goes to the Administrative Appeals Office for independent review. A motion to reopen goes back to the same office and asks it to reconsider based on new evidence or a misapplication of law. If your denial came down to missing documents rather than a fundamental eligibility problem, a motion to reopen with those documents attached is often faster.

The Tax Surprise That Comes with the Discovery

If you derived citizenship as a child but have been living abroad, the United States has been expecting income tax returns and foreign account reports from you for your entire adult life. The IRS doesn’t excuse the obligation because you didn’t know.

Two reporting requirements do the most damage. Any U.S. citizen with foreign financial accounts whose combined value exceeded $10,000 at any point during the year must file FinCEN Form 114, the FBAR.¹³ The $10,000 is a combined total across all accounts, so two accounts holding $6,000 each triggers the filing.

FATCA reporting on Form 8938 kicks in above higher, location-based thresholds. A single filer living abroad triggers the requirement at $200,000 on the last day of the tax year or $300,000 at any point during the year. Living in the United States, single, those numbers drop to $50,000 and $75,000.¹⁴ Form 8938 does not replace the FBAR. You may owe both.

If you’ve never filed and your failure wasn’t deliberate, the IRS streamlined filing compliance procedures offer a path back into compliance without automatic penalties. To qualify, the IRS must not have already opened a civil examination or criminal investigation, and you must certify that your failure to file was non-willful, meaning genuine ignorance or misunderstanding rather than intentional avoidance.¹⁵ Discovering you were a derivative citizen all along is exactly the situation these procedures were built for. The paperwork is dense enough that most people benefit from working with a tax professional who handles international filings.

1
USCIS. Automatic Acquisition of Citizenship after Birth
2
Office of the Law Revision Counsel. 8 USC 1431 – Children Born Outside the United States and Lawfully Residing in the United States
3
U.S. Citizenship and Immigration Services. Deriving Citizenship Before the Child Citizenship Act of 2000
4
GovInfo. 8 USC 1433 – Children Born and Residing Outside the United States
5
USCIS. G-1055, Fee Schedule
6
U.S. Citizenship and Immigration Services. N-600, Application for Certificate of Citizenship
7
U.S. Department of State. Get Citizenship Evidence for a U.S. Passport
8
U.S. Citizenship and Immigration Services. Form I-797C, Notice of Action
9
U.S. Citizenship and Immigration Services. Instructions for Form N-600 Application for Certificate of Citizenship
10
U.S. Citizenship and Immigration Services. Form N-600, Application for Certificate of Citizenship – Frequently Asked Questions
11
USCIS. I-290B, Notice of Appeal or Motion
12
USCIS. Chapter 3 – Appeals
13
Internal Revenue Service. Report of Foreign Bank and Financial Accounts (FBAR)
14
Internal Revenue Service. Summary of FATCA Reporting for U.S. Taxpayers
15
Internal Revenue Service. Streamlined Filing Compliance Procedures