What Is a Social Security Number (SSN)

A Social Security Number (SSN) is a numerical identifier assigned to U.S. citizens and some residents to track their income and determine benefits. The Social Security Number was created in 1935 as part of The New Deal as a program to provide for retirement and disability benefits for the old and infirm. While the original intention of the program and the individually-assigned identification number was simply to track earnings and provide benefits, it is now also used for a wide range of purposes, such as to identify individuals for tax purposes, to track their credit record and approve for credit. In the United States, an individual is asked to provide an SSN to obtain credit, open a bank account, obtain government benefits or private insurance, and to buy a home or a car, among many other pursuits.

How Social Security Numbers (SSN) Work

With very few exceptions, all U.S. legal residents (citizens, permanent residents, and temporary/working residents) have a Social Security Number. Even non-working residents (citizens and non-citizens alike) will have an SSN because of how useful it is to businesses and government entities. The legal framework for assigning a Social Security Number is provided under Section 205(c)(2) of the Social Security Act (42 U.S. Code, Chapter 7, Subsection 405). Social Security Numbers and cards are issued by the Social Security Administration (SSA).

Social Security numbers are now random streams of digits, but prior to 2011, they were not. At that time, the first three digits represented the area in which the individual was born or was from. The next pair of numbers was originally slated to represent a year or month of birth. Because they worried about this being falsified, the Social Security Administration instead voted to have it represent a group number. The final four digits have always been randomly generated. Thus far, no Social Security Numbers have been reused, though there have been some cases in which two people were issued the same number.

Social Security Number (SSN): How to Get One

A Social Security Number (and card) may be obtained by filling out Form SS-5 (Application for a Social Security Card) from the Social Security Administration. The form covers obtaining an original card, replacing a card and changing or correcting SSN records. A full list of requirements (such as documentation that proves age, identity and U.S. citizenship/immigration status) are listed in the form. There is no cost for obtaining a card or number. In some circumstances, an individual may change their Social Security Number.

Social Security Number (SSN) and Identity Theft

Since the Social Security Number is used so frequently as a personal identifier and to obtain credit, and it contains no biometrics and relies on documentation to prove validity, it is susceptible to use for identity theft and fraud. A notable example is when the CEO of identity theft prevention service LifeLock used his SSN in advertisements as a testament to his company's effectiveness. His identity was later stolen multiple times. There has been some movement among legislators to separate some activities from SSN use, such as renting an apartment or obtaining a hunting or fishing license.