Are You a U.S. Citizen? How to Find Out and What It Means for Your Taxes
- U.S. citizenship can be acquired at birth — including by descent through a U.S. citizen parent — without ever having lived in the United States
- If you hold U.S. citizenship, you are required to file a U.S. tax return each year on your worldwide income, regardless of where you live or where your income comes from
- Many people discover their U.S. citizenship status for the first time as adults — often through a bank’s FATCA compliance process or research prompted by a major life event
- AET cannot make a legal determination of citizenship status, but can help guide you through the discovery process and connect you with the right resources
The United States is one of only two countries in the world that taxes on the basis of citizenship rather than residency. If you are a U.S. citizen — regardless of where you were born, where you live, or whether you have ever set foot in the United States — you are required to file a U.S. federal tax return each year reporting your worldwide income.
This filing obligation exists even if you owe no U.S. tax, even if all of your income is earned and taxed in another country, and even if you hold citizenship in another country as well. It is a lifetime obligation that begins at birth and ends only upon formal renunciation or relinquishment of citizenship — and even then, specific tax requirements apply in the year of expatriation.
For many people, the surprise is not the obligation itself but the discovery that they hold U.S. citizenship at all. U.S. citizenship acquired by descent — through a parent or in some cases a grandparent — does not require any affirmative act on the part of the person. It exists from birth, whether or not the person is aware of it, and so do the associated tax obligations.
U.S. citizenship is acquired in one of two ways: at birth, or through naturalization. The rules for each are governed by the Immigration and Nationality Act (INA) and have changed significantly over time — meaning the law in effect at the time of your birth determines your citizenship status, not the current law.
Amendment XIV, Section 1 of the U.S. Constitution establishes that all persons born on U.S. soil are U.S. citizens. This applies regardless of the immigration or tax status of the person’s parents — with a narrow exception for children born to foreign diplomats with full diplomatic immunity.
U.S. soil for this purpose includes the fifty states, the District of Columbia, Puerto Rico, Guam, the U.S. Virgin Islands, and the Northern Mariana Islands. It does not include U.S. military bases or embassies located in foreign countries.
If you were born in the United States — even if you left as an infant and have never returned — you are a U.S. citizen and have U.S. tax filing obligations.
U.S. citizenship can also be acquired at birth by a child born outside the United States if at least one parent was a U.S. citizen at the time of the child’s birth and met applicable residency or physical presence requirements in the United States prior to the birth. The specific requirements depend on the law in effect at the time of birth and the citizenship status of each parent.
The following table summarizes the general provisions of the INA for children born abroad. Note that these provisions have been subject to significant legislative changes over time — the law at the time of your birth applies, not the current version.
| INA Section | Parent Status | U.S. Residency / Presence Requirement | Citizenship Acquired |
| 301(c) | Both parents are U.S. citizens | At least one parent resided in the U.S. or outlying possessions prior to child’s birth | At birth |
| 301(d) | One parent is a U.S. citizen; other parent is a U.S. national but not a citizen | U.S. citizen parent physically present in the U.S. or outlying possessions for one year prior to birth | At birth |
| 301(f) | Unknown parentage | Child found in the United States while under age 5 | At birth |
| 301(g) | One parent is a U.S. citizen; other parent is a foreign national | U.S. citizen parent physically present in the U.S. or outlying possessions for at least 5 years, including 2 years after age 14, prior to birth | At birth |
| 301(h) | Mother is a U.S. citizen; father is a foreign national | U.S. citizen mother resided in the U.S. prior to birth; child born outside U.S. jurisdiction | At birth (births prior to May 24, 1934 only) |
| 309(a) | Out of wedlock birth — claiming citizenship through father | Requirements depend on applicable INA provision | At birth |
| 309(c) | Out of wedlock birth — claiming citizenship through mother | U.S. citizen mother physically present in the U.S. or outlying possessions for one year prior to birth | At birth (births after December 23, 1952) |
| 320 | At least one parent is a U.S. citizen by birth or naturalization | Child resides in the U.S. as a lawful permanent resident | At time criteria is met |
| 322 | At least one parent is a U.S. citizen by birth or naturalization | Child resides outside the U.S.; parent or grandparent physically present in the U.S. for at least 5 years including 2 after age 14; child is under 18 | At time oath is administered |
This table is a general reference only. Citizenship determinations are complex, fact-specific, and depend on the law in effect at the time of birth. AET cannot make a legal determination of citizenship status — for a formal determination, contact USCIS or the U.S. Embassy or Consulate in your country of residence.
Naturalization is the process through which non-citizens apply for and are granted U.S. citizenship by fulfilling the requirements set out in the Immigration and Nationality Act. The standard naturalization process requires a period of lawful permanent residence, physical presence, and other criteria.
A simplified naturalization process exists for certain individuals with U.S. citizenship in their family background — including children of U.S. citizens who did not acquire citizenship at birth. The Child Citizenship Act of 2000 also automatically conferred citizenship on certain children who were lawful permanent residents of the United States when the Act took effect.
If you were naturalized as a U.S. citizen — or if you naturalized as a minor when a parent naturalized — you hold U.S. citizenship and have the same worldwide filing obligations as any other U.S. citizen.
If you are unsure whether you hold U.S. citizenship, the following steps are a useful starting point:
Review your family history. Were either of your parents born in the United States or known to be U.S. citizens? Were you born in the United States? Did you or a parent ever go through a naturalization process? The INA table above can help you assess whether citizenship by descent may apply to your situation.
Contact USCIS. The U.S. Citizenship and Immigration Services National Customer Service Center can be reached at 1-800-375-5283. Canadian inquiries can be directed by email to [email protected]. The USCIS website at uscis.gov provides additional resources including the full text of the INA and the USCIS Policy Manual.
Contact the U.S. Embassy or Consulate. The U.S. Embassy or Consulate in your country of residence can provide guidance on citizenship determination and, if applicable, assist with the process of obtaining a U.S. passport or Certificate of Citizenship as evidence of your status.
Consult a U.S. immigration attorney. For complex situations — particularly those involving citizenship by descent under historical versions of the INA — an immigration attorney is better positioned than a tax firm to provide a definitive determination.
Contact AET. While we cannot make a legal determination of citizenship status, we can help you think through your situation, identify the right questions to ask, and connect you with appropriate resources. If you discover that you do hold U.S. citizenship and have unfiled returns, we can guide you through the compliance process.
Once you have determined that you hold U.S. citizenship, the tax implications are straightforward in principle — though the details can be complex depending on your financial situation.
Annual filing obligation. You are required to file a U.S. federal tax return each year reporting your worldwide income. The return is due April 15, with an automatic two-month extension to June 15 for U.S. persons living outside the United States, and a further extension to October 15 available on request.
Worldwide income reporting. All income from all sources — employment, self-employment, investments, rental property, pensions, and any other source — must be reported on your U.S. return, regardless of where it is earned or whether it has already been taxed in another country.
Double taxation protection. The Foreign Tax Credit and Foreign Earned Income Exclusion are designed to prevent U.S. citizens abroad from being taxed twice on the same income. Most expats living in countries with comparable tax rates owe little or no U.S. tax after these are applied. The obligation is primarily one of filing, not payment.
Information returns. In addition to the tax return itself, various information returns may be required depending on your financial situation — including the FBAR, Form 8938, Forms 3520 and 3520A for foreign trusts, and Form 5471 for ownership interests in foreign corporations. See our guide to U.S. filing obligations for Americans abroad →Coming into compliance. If you have discovered your U.S. citizenship status and have never filed U.S. returns, the Streamlined Foreign Offshore Procedures provide a structured path to compliance without penalties in most cases. See our Streamlined Filing Compliance Procedures guide
Frequently Asked Questions
Yes. U.S. citizenship acquired at birth by virtue of being born on U.S. soil is automatic and does not depend on residence, upbringing, or any affirmative act. If you were born in the United States — including U.S. territories — you are a U.S. citizen and have U.S. tax filing obligations.
Possibly — it depends on whether your mother met the applicable residency or physical presence requirements in the United States prior to your birth, and on the law in effect at the time you were born. The INA table above is a starting point, but a formal determination from USCIS or a U.S. immigration attorney is the right next step for a definitive answer.
No. The United States does not recognize dual citizenship as a basis for reducing or eliminating U.S. tax obligations. Holding citizenship in another country does not exempt you from U.S. filing requirements. You remain subject to U.S. worldwide income reporting as long as you hold U.S. citizenship.
Not necessarily. Citizenship by birth or descent exists from the moment the legal criteria are met — it does not require any affirmative application or registration. Never having applied for a U.S. passport or Social Security number is common among people who discover their citizenship as adults, and does not affect the underlying citizenship status or the associated tax obligations.
Renunciation is a significant legal decision with implications beyond tax. From a tax perspective, you must have filed five years of U.S. tax returns before your renunciation is recognized for tax purposes — meaning coming into compliance is a prerequisite, not something you can avoid by renouncing. Renunciation may also trigger an exit tax depending on your financial situation. If you are considering renunciation, a consultation with an AET Tax Specialist is a useful starting point to understand the tax implications before proceeding.
The Streamlined Foreign Offshore Procedures allow eligible U.S. persons living abroad to come into compliance by filing three years of tax returns and six years of FBARs without penalties, provided the non-compliance was non-willful. For most people who were simply unaware of their U.S. citizenship and its associated obligations, the non-willful standard is met. See our Streamlined Filing guide → or book a consultation to discuss your specific situation.
For tax purposes, “U.S. person” is a broader category that includes U.S. citizens, green card holders, and resident aliens under the Substantial Presence Test. The filing obligations discussed in this article apply to all U.S. persons — not just citizens. See our guide to U.S. filing requirements for Americans abroad → for a full breakdown by status.
