{"id":18,"date":"2026-07-22T02:52:01","date_gmt":"2026-07-22T02:52:01","guid":{"rendered":"https:\/\/fedlaws.org\/?p=18"},"modified":"2026-07-22T02:52:01","modified_gmt":"2026-07-22T02:52:01","slug":"do-us-citizens-have-an-alien-registration-number","status":"publish","type":"post","link":"https:\/\/fedlaws.org\/?p=18","title":{"rendered":"Do US Citizens Have an Alien Registration Number?"},"content":{"rendered":"

People born as U.S. citizens do not have an alien registration number. The federal government only assigns that identifier to non-citizens, so if you acquired citizenship at birth, no A-number exists in your name. Naturalized citizens are the exception: they were assigned an alien registration number during their time as non-citizens, and that number stays in their immigration records permanently.1<\/a><\/sup>U.S. Citizenship and Immigration Services. A-Number\/Alien Registration Number\/Alien Number<\/a><\/span><\/p>\n

What an Alien Registration Number Is<\/h2>\n

An alien number, commonly called an A-number, is the letter “A” followed by eight or nine digits, for example A012345678. If the number has fewer than nine digits, a zero is added after the “A” to pad it out.2<\/a><\/sup>U.S. Citizenship and Immigration Services. Immigrant Fee Payment: Tips on Finding Your A-Number and DOS Case ID<\/a><\/span> The Department of Homeland Security assigns it to any non-citizen who interacts with the immigration system, whether through a green card application, work authorization request, or removal proceedings.<\/p>\n

On green cards issued after May 10, 2010, the same number appears labeled as “USCIS Number.” It is the same identifier as the A-number, just without the “A” prefix.3<\/a><\/sup>U.S. Citizenship and Immigration Services. USCIS Number<\/a><\/span><\/p>\n

Why Citizens by Birth Have No A-Number<\/h2>\n

If you were born in the United States, or born abroad to U.S. citizen parents and never held any immigration status, you have no reason to have entered the immigration system in the first place. The government tracks U.S. citizens through Social Security numbers, not immigration identifiers. No A-number was ever created for you, and none will be.<\/p>\n

This matters when you’re filling out forms that ask for one. If a document requests an alien registration number and you were born a citizen, the honest and correct answer is that you do not have one. Leaving the field blank or marking it not applicable is appropriate.<\/p>\n

Why Naturalized Citizens Have One<\/h2>\n

If you became a U.S. citizen through naturalization, you have an A-number. It was assigned to you the moment you entered the immigration system, whether by receiving a green card, applying for asylum, or being granted another immigration benefit. The naturalization process itself required you to list that A-number on Form N-400, and USCIS used it to link the application to your existing file.4<\/a><\/sup>U.S. Citizenship and Immigration Services. Form N-400, Instructions for Application for Naturalization<\/a><\/span><\/p>\n

Naturalization does not erase the number. It stays in your immigration file permanently, even though your Certificate of Naturalization becomes your primary proof of citizenship afterward and your daily interactions with government agencies shift to your Social Security number. The A-number is still there in your record, and you may need to reference it in specific situations later on.<\/p>\n

Children Who Became Citizens Through a Parent<\/h3>\n

Children born outside the United States can automatically acquire citizenship under Section 320 of the Immigration and Nationality Act if they meet four conditions: at least one U.S. citizen parent, under 18, lawful permanent residents, and residing in the U.S. in the custody of the citizen parent.5<\/a><\/sup>U.S. Citizenship and Immigration Services. Automatic Acquisition of Citizenship after Birth (INA 320)<\/a><\/span> Because they had to become lawful permanent residents first, they too were assigned an A-number, and it stays in their records after citizenship takes effect.<\/p>\n

Parents documenting this citizenship file Form N-600, Application for Certificate of Citizenship, which asks for the child’s alien registration number.6<\/a><\/sup>U.S. Citizenship and Immigration Services. I am the Child of a U.S. Citizen<\/a><\/span><\/p>\n

When You’ll Still Need Your A-Number as a Citizen<\/h2>\n

The most common reason a naturalized citizen has to dig up their A-number is petitioning for a family member to immigrate. When you file Form I-130, Petition for Alien Relative, USCIS uses your A-number to connect the new petition to your prior immigration history.7<\/a><\/sup>U.S. Citizenship and Immigration Services. Instructions for Form I-130, Petition for Alien Relative<\/a><\/span><\/p>\n

You may also need it when requesting copies of your immigration records through a Freedom of Information Act request, replacing a lost naturalization certificate, or applying for a U.S. passport for the first time as a new citizen. The Social Security Administration also verifies alien registration numbers with DHS when processing certain benefits, using the Systematic Alien Verification for Entitlements program.8<\/a><\/sup>Social Security Administration. Procedure for Verifying a Persons Status with the Department of Homeland Security<\/a><\/span><\/p>\n

Where to Find Your A-Number<\/h2>\n

If you’re a naturalized citizen who needs to locate your A-number, it appears on several documents you likely already have:<\/p>\n