A Social Security Number is a nine-digit identifier the federal government assigns to you

Your Social Security Number (SSN) is a unique nine-digit code issued by the Social Security Administration. The format is XXX-XX-XXXX. The government uses it to track your earnings record, calculate your benefits when you retire or become disabled, and verify your identity for tax purposes. Private employers, banks, and other institutions also use it to report income and manage accounts in your name.

You do not need to do anything to "activate" an SSN once you receive it — it is automatically valid. The number itself does not expire, though you may request a replacement if yours is lost, stolen, or used fraudulently. Most people receive their first SSN as infants, but you can request one at any age if you are a U.S. citizen or authorized work resident.

Key Takeaways

  • A Social Security Number is a nine-digit identifier assigned by the Social Security Administration to track earnings and benefits.
  • You need an SSN to work legally in the United States, file taxes, and open bank accounts or credit lines.
  • The number is issued once and does not change unless you request a replacement due to loss, theft, or fraud.
  • You can request an SSN at any age if you are a U.S. citizen or authorized to work, by visiting your local Social Security office with proof of identity and citizenship.

What the nine digits mean

The Social Security Number breaks into three parts. The first three digits are the area number, which originally indicated the state where you applied for the number, though this is no longer strictly true. The middle two digits are the group number. The last four digits are the serial number. Together, these create a unique identifier for one person.

The Social Security Administration does not assign numbers in a predictable sequence, so you cannot guess someone else's number or create a fake one that will pass verification. The agency also does not reuse numbers after a person dies, so each SSN issued remains tied to one individual for record-keeping purposes.

Why you need one and what it is used for

An SSN is required to work legally in the United States. Your employer uses it to report your wages to the Internal Revenue Service and to withhold taxes from your paycheck. If you are self-employed, you report your income using your SSN on your tax return. Banks and credit card companies use it to check your credit history and report your account activity to credit bureaus.

The Social Security Administration uses your SSN to maintain your earnings record — the total amount you have earned over your working life. This record determines how much you will receive in retirement benefits, disability benefits, or survivor benefits if you become unable to work or die. Government agencies also use your SSN to verify your identity when you apply for benefits, loans, or licenses.

Private companies may ask for your SSN for reasons unrelated to government benefits. A doctor's office, utility company, or insurance provider might request it to identify your account or report information to credit bureaus. You are not required to provide your SSN in all situations — you can ask why it is needed and whether an alternative identifier will work.

How to get a Social Security Number

If you are a newborn, your parent or guardian can request an SSN at the hospital or through the Social Security Administration after birth. You will need a birth certificate, proof of citizenship (such as a U.S. passport), and proof of identity for the parent or guardian. The process takes about two weeks.

If you are an adult and do not have an SSN, visit your local Social Security office in person. Bring an original or certified copy of your birth certificate, a government-issued photo ID (such as a passport or driver's license), and proof of citizenship or work authorization. If you are not a U.S. citizen, you must show an immigration document proving you are authorized to work in the United States. The office will issue a temporary receipt and mail your SSN card within two weeks.

You cannot request an SSN by mail or online. You must apply in person at a Social Security office. To find the office nearest you, visit the Social Security Administration website or call 1-800-772-1213.

Replacing a lost, stolen, or fraudulently used number

If your SSN card is lost or stolen, you can request a replacement at your local Social Security office. Bring your photo ID and proof of citizenship. There is no cost, and you can request up to three replacement cards in a year and ten in your lifetime. The replacement card will have the same nine-digit number — the Social Security Administration does not issue a new number unless you can prove your SSN has been used fraudulently.

If you suspect your SSN has been used to open accounts, file taxes, or commit fraud in your name, report it to the Federal Trade Commission at IdentityTheft.gov. You can also contact the Social Security Administration's fraud hotline at 1-800-269-0271. The agency will investigate and may issue you a new SSN if the fraud is severe and ongoing, though this is rare and requires documented evidence.

Protecting your Social Security Number

Your SSN is sensitive information. Do not share it with anyone unless you have a clear reason — such as an employer, bank, or government agency. Scammers often call or email claiming to be from the Social Security Administration and threatening to suspend your benefits unless you provide your SSN. The Social Security Administration will never call you unsolicited or threaten you. If you receive such a call, hang up and report it to the Office of Inspector General at 1-800-269-0271.

Shred documents that contain your SSN before discarding them. Do not carry your SSN card in your wallet unless necessary. If you are asked for your SSN in a situation where it seems unnecessary — such as at a retail store or doctor's office — you can ask whether providing it is truly required or whether an alternative identifier will work.

Frequently Asked Questions

Can I change my Social Security Number?

You can request a new SSN only if you can document that your current number has been used fraudulently or that you are in danger because of your number. The Social Security Administration rarely issues new numbers. If you lose your card, you receive a replacement card with the same nine-digit number.

Do I need to carry my Social Security card with me?

No. You only need your SSN when applying for a job, opening a bank account, filing taxes, or applying for government benefits. Carrying the physical card increases the risk of loss or theft. You can memorize your number or keep it in a secure location at home.

What happens to my Social Security Number when I die?

Your SSN remains in the Social Security Administration's records permanently. The agency does not reuse the number. Your family members may use your SSN to report your death to creditors and government agencies, but the number itself is not transferred or reassigned.

Can I get a Social Security Number if I am not a U.S. citizen?

Yes, if you are authorized to work in the United States. You must show an immigration document proving your work authorization, such as an Employment Authorization Document (EAD) or visa. Undocumented immigrants cannot obtain an SSN through the Social Security Administration.