US Social Security Number: How It Works, Who Qualifies, How to Apply

A U.S. Social Security number is a free, nine-digit identifier the Social Security Administration issues to track your lifetime earnings and determine what you’ll collect in retirement, disability, and survivor benefits.¹ It has also grown into the country’s default identification number for tax filing, employment verification, credit reporting, and government services. Most Americans get theirs at birth through the hospital, and the card itself never costs anything.²

What the Number Actually Does

Congress created the SSN in 1935 to record wages under the new Social Security Act.³ When you work, your employer withholds Federal Insurance Contributions Act taxes from each paycheck and credits them to your account using your number. The total you earn over your career is what drives the size of your future benefit check.⁴

One thing worth knowing if you’re trying to guess something about a number: since June 25, 2011, the SSA has assigned numbers randomly. Before that, the first three digits reflected the state where you applied. Numbers issued today carry no geographic meaning.⁵

Who Qualifies for an SSN

Three groups of people can be assigned a Social Security number:

U.S. citizens, whether by birth or naturalization, qualify automatically.⁶
Lawful permanent residents with a green card qualify with full work authorization.⁷
Temporary visa holders with permission from the Department of Homeland Security to work in the United States qualify for a number tied to that authorization.⁶

There is a narrower fourth path. Non-citizens without work authorization can sometimes get a non-work SSN when a federal law requires one to receive a federally funded benefit they’re otherwise entitled to, or when a state or local law requires one for public assistance and they’re legally in the country.⁸ Cards issued this way are printed with the legend “Not Valid for Employment.”⁹

Getting a Number at Birth

The easiest way to get an SSN for a newborn is the Enumeration at Birth program. When you register the birth at the hospital or birthing center, you can request a Social Security number on the same form. The state vital statistics office then sends the birth data electronically to the SSA, which assigns a number, prints the card, and updates its records without any additional paperwork from you.¹⁰

The national average processing time is about two weeks, and the card typically arrives in the mail about two weeks after that.¹⁰ If you skipped the hospital option, you’ll need to apply through the standard process instead.

How to Apply for an Original Card

Start with Form SS-5, the Application for a Social Security Card.¹¹ The form asks for your full name at birth, your parents’ Social Security numbers if you know them, your date and place of birth, and your mailing address. You can download it from ssa.gov or pick one up at a local office.

You’ll then need to prove three things with original documents (or copies certified by the issuing agency, since the SSA does not accept photocopies or notarized copies):

Age. A U.S. birth certificate is the usual proof. A passport works too.
Identity. A current document with your name and biographical information, such as a driver’s license, state ID, or U.S. passport.
Citizenship or immigration status. For citizens, a U.S. birth certificate or passport handles this. Non-citizens need a DHS document such as a Permanent Resident Card (Form I-551), an Arrival/Departure Record (Form I-94) with an unexpired foreign passport, or an Employment Authorization Document (Form I-766).¹²

One document can cover more than one requirement. A U.S. passport, for example, proves both age and citizenship, and the SSA encourages using as few documents as possible.²

Bring the completed form and your originals to your nearest Social Security office; use the locator on ssa.gov to find it.¹³ A representative reviews the documents in person and hands your originals back. If everything checks out, the card arrives in the mail within about 7 to 10 business days.¹⁴

Replacing or Correcting a Card

If you’re a U.S. citizen with a driver’s license or state ID, you can request a replacement online through your personal my Social Security account at ssa.gov. In most states, the whole process finishes online with no office visit.¹⁵ If online won’t work in your case, you can start there and schedule an in-person appointment to finish. Otherwise, the in-person process is the same as a first-time application: Form SS-5, original documents, local office. Replacements are free.²

Federal rules cap replacement cards at three per calendar year and ten per lifetime for cards issued on or after December 17, 2005, under the Intelligence Reform and Terrorism Prevention Act of 2004.⁹¹⁶ Several situations don’t count against those caps: legal name changes, changes to the restrictive legend after an immigration update, non-receipt of a card the SSA already processed, and SSA errors. If you’ve hit the limit for another reason, you can still request an exception by showing significant hardship, such as a referral letter from an agency that needs to see the card to provide services.

Changing Your Name

After a legal name change through marriage, divorce, or a court order, get an updated card so your earnings continue to post correctly. Submit Form SS-5 with an original or certified copy of a marriage document, divorce decree, certificate of naturalization showing the new name, or court order approving the change.¹⁷ Name-change cards do not count against the three-per-year or ten-per-lifetime caps.⁹

When the SSA Will Give You a Different Number

A replacement card carries the same number you already have. In a short list of situations, the SSA will instead assign you a new nine-digit number:¹⁸

You’re a victim of ongoing identity theft, you’ve tried to fix it, and misuse of the original number is still harming you.
You face harassment, abuse, or a threat to your life.
Two or more family members received sequential numbers that are causing confusion.
Someone else has been assigned or is using the same number.
You have a documented religious or cultural objection to specific digits.

A stolen card or a data breach alone is not enough. You’ll need to show that the original number itself keeps causing problems you can’t resolve any other way. To start, contact your local office for an in-person appointment.¹⁸

If You Don’t Qualify: The ITIN

If you don’t qualify for an SSN but you still have to file a federal tax return, the IRS issues a separate nine-digit number called an Individual Taxpayer Identification Number. ITINs are available to resident and nonresident aliens with a filing obligation, along with their spouses and dependents.¹⁹

An ITIN is strictly for tax processing. It does not authorize work, change your immigration status, make you eligible for Social Security benefits or the Earned Income Tax Credit, or function as ID outside the federal tax system.¹⁹ If your status later changes and you become eligible for an SSN, apply for the SSN and stop using the ITIN.

Protecting Your Number

The SSA’s own guidance is direct: don’t carry the card in your wallet, and don’t say the number aloud in public places.²⁰

No federal law broadly stops private businesses from asking for your SSN. Section 7 of the Privacy Act of 1974 bars government agencies from denying you a right or benefit for refusing to disclose it, but that protection does not reach private companies.²¹ Banks, landlords, and employers usually do need it. Plenty of other businesses ask when they don’t, and you can always ask whether disclosure is legally required or just preferred.

If your number is exposed in a breach or stolen, the SSA recommends freezing your credit with the three major bureaus and watching your accounts for unusual activity. A my Social Security account lets you spot unauthorized changes to your record. If someone uses the number to open accounts or make purchases, report it at IdentityTheft.gov to get a recovery plan and an FTC Identity Theft Report. For a stronger lock, the SSA offers two optional blocks on your account: an eServices block that prevents anyone from viewing or changing your information online, and a Direct Deposit Fraud Prevention block that stops changes to your payment routing. Both require an in-person visit to remove, which is what makes them useful against remote fraud.²⁰

1
Social Security Administration. Meaning of the Social Security Number
2
Social Security Administration. Frequently Asked Questions – Social Security Numbers and Immigrant Visas
3
Social Security Administration. Social Security Act of 1935
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Social Security Administration. What is FICA?
5
Social Security Administration. Social Security Number Randomization
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Social Security Administration. 20 CFR 422.104 – Who Can Be Assigned a Social Security Number
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Social Security Administration. Apply for Your Social Security Card While Applying for Your Work Permit, Lawful Permanent Residency, or U.S. Naturalization
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Social Security Administration. Social Security Numbers for Noncitizens
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eCFR. 20 CFR 422.103 – Social Security Numbers
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Social Security Administration. What is Enumeration at Birth and How Does It Work?
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Social Security Administration. Form SS-5 – Application for a Social Security Card
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Social Security Administration. Learn What Documents You Will Need to Get a Social Security Card
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Social Security Administration. Request a Social Security Number for the First Time
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Social Security Administration. How Long Will It Take to Get a Social Security Card?
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Social Security Administration. How Do I Apply for a Replacement Social Security Number Card?
16
Social Security Administration. Limits on Replacement SSN Cards
17
Social Security Administration. U.S. Citizen – Adult Name Change on Social Security Card
18
Social Security Administration. Can I Change My Social Security Number?
19
Internal Revenue Service. Individual Taxpayer Identification Number (ITIN)
20
Social Security Administration. Fraud Prevention and Reporting
21
Social Security Administration. PL 93-579, Approved December 31, 1974