The Social Security Administration assigns numbers through a system that has changed significantly over time

The Social Security Administration (SSA) assigns a nine-digit Social Security number to nearly every person born in the United States, as well as to many non-citizens who work or pay taxes. The number itself is not random — it follows a structure where the first three digits (the area number), the middle two digits (the group number), and the last four digits (the serial number) each carry specific meaning about when and where your number was issued.

Until 2011, the SSA assigned numbers based on geography: the area number corresponded to the state where you applied for your number, usually the state where you were born. Starting in June 2011, the SSA switched to randomization, meaning new numbers no longer reveal where someone was born or applied. This change was made partly to reduce identity theft, since the old system made numbers easier to predict and forge.

Most people receive their number automatically as infants through a process called "enumeration at birth." Parents provide information on the birth certificate, and the SSA issues a number without the family having to request it. Others receive numbers later in life when they first need one for work, school, or other purposes.

Key Takeaways

  • Social Security numbers are assigned by the SSA to U.S. citizens, permanent residents, and many non-citizens who work or pay taxes.
  • Before 2011, the first three digits indicated the state where someone applied for their number; since 2011, all new numbers are randomized.
  • Infants typically receive numbers automatically through enumeration at birth, with no action required from parents.
  • Adults who need a number for the first time must visit an SSA office in person with proof of identity, age, and citizenship or immigration status.

How the numbering system is structured

A Social Security number has three parts. The area number (first three digits) historically indicated geography but is now random for numbers issued after June 2011. The group number (middle two digits) was never geographic and was assigned in a specific sequence to manage the volume of numbers issued. The serial number (last four digits) is assigned sequentially within each group.

The SSA never issues numbers beginning with 000, 666, or 900–999. It also does not issue numbers where all digits are the same (like 111-11-1111). These restrictions exist to prevent confusion and reduce fraud. If you see a number with these patterns, it is not a valid Social Security number.

For numbers issued before 2011, you can often determine roughly when and where someone applied by looking at the area number. For example, area numbers in the 001–003 range were historically assigned to people in New Hampshire, while 700–728 were assigned in California. However, this geographic link no longer applies to numbers issued after June 2011, making it much harder to guess or forge numbers based on their structure alone.

Enumeration at birth and automatic assignment

Most children born in the United States receive a Social Security number automatically within weeks of birth. This process, called enumeration at birth, began in 1989 and has been standard practice since then. The hospital or birthing facility collects information from the birth certificate, and the SSA issues a number without parents having to visit an office or submit a separate request.

Parents can opt out of enumeration at birth if they choose, though this is rare. If you opt out, you will need to apply for a number later when your child needs one for school, work, or other purposes. To opt out, you must decline at the hospital or contact the SSA directly before the number is issued.

If enumeration at birth did not happen — because you were born before 1989, born outside the United States, or your parents opted out — you can still get a number at any point in your life. The process is the same whether you are applying as a child, teenager, or adult.

Applying for a number as an adult or non-citizen

If you did not receive a number at birth and need one now, you must visit a Social Security office in person. You cannot apply by mail or online. Bring original or certified copies of documents proving your identity, age, and citizenship or immigration status. Acceptable identity documents include a passport, driver's license, or state ID. For age, a birth certificate works. For citizenship, bring your birth certificate if you were born in the U.S., or your immigration documents (like a green card, visa, or employment authorization document) if you are not a citizen.

The SSA will not issue a number to a non-citizen unless that person has work authorization or a specific reason to need one, such as filing taxes or opening a bank account. Temporary visitors without work authorization cannot get a number. Processing typically takes one to two weeks after you submit your application in person.

If you have lost your Social Security card or need a replacement, you can request one by mail or through a Social Security office, depending on your state. You do not need to reapply for a new number — the SSA will issue a new card with your existing number.

Why the SSA switched to randomization in 2011

For decades, the predictable structure of Social Security numbers made them vulnerable to fraud. Because the area number revealed geography and the group and serial numbers followed a known sequence, someone could guess or generate plausible numbers without actually stealing them. This made identity theft easier and allowed fraudsters to create fake numbers that looked legitimate.

In 2011, the SSA began randomizing all three parts of new numbers to eliminate this vulnerability. The change applied only to numbers issued after June 25, 2011. Existing numbers were not changed. The randomization makes it much harder to forge a number or predict what someone's number might be based on where they were born or when they applied.

The switch also removed the geographic stigma that some groups faced. Under the old system, certain area numbers became associated with particular regions or populations, which could lead to discrimination. Randomization eliminated this pattern.

What to do if your number is lost, stolen, or compromised

If your Social Security number has been lost or stolen, contact the SSA immediately by calling 1-800-772-1213 or visiting your local Social Security office. You can also place a fraud alert with the three major credit bureaus (Equifax, Experian, and TransUnion) to make it harder for someone to open accounts in your name. A fraud alert lasts one year and can be renewed.

If you suspect identity theft, file a report with the Federal Trade Commission at IdentityTheft.gov. The FTC will create a recovery plan and provide you with documents to show creditors and law enforcement. You may also want to check your credit report for unauthorized accounts. You can request a free credit report from each bureau once per year at AnnualCreditReport.com.

The SSA can issue you a new number if your old one has been compromised, though this is rare and typically only done after other steps have been taken. A new number does not erase your old one from records — both will remain linked to your account history.

How Social Security numbers connect to your work and tax history

Your Social Security number is the primary identifier the SSA uses to track your earnings record and work history. Every time you work and pay Social Security taxes, your employer reports your wages under your number. The SSA uses this record to calculate your future benefits, whether you become disabled, and how much you will receive in retirement.

You can view your earnings record by creating an account on ssa.gov and accessing your Social Security Statement. This statement shows your reported earnings year by year and estimates what your retirement, disability, and survivor benefits might be. Checking this record periodically helps you catch errors or signs of fraud early.

Your number is also used by the Internal Revenue Service (IRS) to match your tax returns to your earnings record. If there are discrepancies — for example, if your employer reports different wages than you claim on your taxes — the IRS and SSA will investigate.

Frequently Asked Questions

Can I change my Social Security number if I do not like it?

The SSA will not change your number simply because you do not like it. A new number is issued only if your old one has been compromised by identity theft or fraud, and even then only after you have taken other protective steps. Once issued, your number stays with you for life.

What if there is an error in my Social Security number on my birth certificate?

Contact the SSA with your birth certificate and proof of identity. The SSA can correct errors in their records if you provide documentation. You may also need to correct the birth certificate itself through your state's vital records office, depending on what the error is.

Do non-citizens need a Social Security number?

Not all non-citizens need one, but many do. If you work in the U.S., you need a number. If you pay taxes, file a tax return, or open a bank account, you typically need one. Temporary visitors without work authorization cannot get a number. Check with the SSA or an immigration attorney about your specific situation.

How long does it take to get a Social Security number?

For infants, enumeration at birth usually takes a few weeks. For adults applying in person, processing typically takes one to two weeks after you submit your application. During high-volume periods, it may take longer.

Is my Social Security number the same as my tax ID?

For most people, yes — your Social Security number serves as your tax identification number. However, non-citizens who do not have a Social Security number can get an Individual Taxpayer Identification Number (ITIN) from the IRS to file taxes. An ITIN is used only for tax purposes and does not give you work authorization or Social Security benefits.