Social Security number

A Social Security card issued by the Railroad Retirement Board in 1943 to a now deceased person.

In the United States, a Social Security number (SSN) is a nine-digit number issued to U.S. citizens, permanent residents, and temporary (working) residents under section 205(c)(2) of the Social Security Act, codified as 42 U.S.C. § 405(c)(2). The number is issued to an individual by the Social Security Administration, an independent agency of the United States government. Although its primary purpose is to track individuals for Social Security purpopses,[1] the Social Security number has become a de facto national identification number for taxation and other purposes.[2]

A Social Security number may be obtained by applying on Form SS-5, application for A Social Security Number Card.[3]


  • 1 History
  • 2 Purpose and use
    • 2.1 Non-universal status
    • 2.2 Use required for federal tax purposes
  • 3 Types of Social Security cards
  • 4 Identity theft
  • 5 Replacement numbers
  • 6 Structure
    • 6.1 Historical structure
    • 6.2 Valid SSNs
    • 6.3 Exhaustion and re-use
  • 7 SSNs used in advertising
  • 8 List of Social Security Area Numbers
  • 9 See also
  • 10 References
  • 11 External links


Social Security numbers were first issued by the Social Security Administration in November 1935 as part of the New Deal Social Security program. Within three months, 25 million numbers were issued.[4]

On November 24, 1936, 1,074 of the nation’s 45,000 post offices were designated “typing centers” to type up Social Security cards that were then sent to Washington, D.C. On December 1, 1936, as part of the publicity campaign for the new program, Joseph L. Fay of the Social Security Administration selected a record from the top of the first stack of 1,000 records and announced that the first Social Security number in history was assigned to John David Sweeney, Jr., of New Rochelle, New York.[5][6]

Before 1986, people often did not obtain a Social Security number until the age of about 14,[7] since the numbers were used for income tracking purposes, and those under that age seldom had substantial income.[8] The Tax Reform Act of 1986 required parents to list Social Security numbers for each dependent over the age of 5 for whom the parent wanted to claim a tax deduction.[9] Before this act, parents claiming tax deductions were simply trusted not to lie about the number of children they supported. During the first year of the Tax Reform Act, this anti-fraud change resulted in seven million fewer minor dependents being claimed. The disappearance of these dependents is believed to have involved either children who never existed or tax deductions improperly claimed by non-custodial parents.[10] In 1988, the threshold was lowered to 2 years old, and in 1990, the threshold was lowered yet again to 1 year old.[11] Today, an SSN is required regardless of the child’s age to receive an exemption.[citation needed] Since then, parents have often applied for Social Security numbers for their children soon after birth; today, it can be done on the application for a birth certificate.[12]

Purpose and use[edit]

The original purpose of this number was to track individuals’ accounts within the Social Security program. It has since come to be used as an identifier for individuals within the United States, although rare errors occur where duplicates do exist. As numbers are now assigned by the central issuing office of the SSA, it is unlikely that duplication will ever occur again. A few duplications did occur when prenumbered cards were sent out to regional SSA offices and (originally) Post Offices.

Employee, patient, student, and credit records are sometimes indexed by Social Security number.

The U.S. Armed Forces has used the Social Security number as an identification number for Army and Air Force personnel since July 1, 1969, the Navy and Marine Corps for their personnel since January 1, 1972, and the Coast Guard for their personnel since October 1, 1974.[13] Previously, the United States military used a much more complicated system of service numbers that varied by service.

Beginning in June 2011, DOD began removing the Social Security number from military identification cards. It is replaced by a unique DOD identification number, formerly known as the EDIPI.[14]

Non-universal status[edit]

An old Social Security card with the “not for identification” message

Social Security was originally a universal tax, but when Medicare was passed in 1965, objecting religious groups in existence prior to 1951 were allowed to opt out of the system.[15] Because of this, not every American is part of the Social Security program, and not everyone has a number. However, a social security number is required for parents to claim their children as dependents for federal income tax purposes,[12] and the Internal Revenue Service requires all corporations to obtain SSNs (or alternative identifying numbers) from their employees, as described below. The Old Order Amish have fought to prevent universal Social Security by overturning rules such as a requirement to provide a Social Security number for a hunting license.[16]

Social Security cards printed from January 1946 until January 1972 expressly stated that people should not use the number and card for identification.[17] Since nearly everyone in the United States now has an SSN, it became convenient to use it anyway and the message was removed.[18]

Since then, Social Security numbers have become de facto national identification numbers.[2] Although some people do not have an SSN assigned to them, it is becoming increasingly difficult to engage in legitimate financial activities such as applying for a loan or a bank account without one.[19] While the government cannot require an individual to disclose their SSN without a legal basis, companies may refuse to provide service to an individual who does not provide an SSN.[20][21] The card on which an SSN is issued is still not suitable for primary identification as it has no photograph, no physical description and no birth date. All it does is confirm that a particular number has been issued to a particular name. Instead, a driver’s license or state ID card is used as an identification for adults.

Use required for federal tax purposes[edit]

Internal Revenue Code section 6109(d) provides: “The social security account number issued to an individual for purposes of section 205(c)(2)(A) of the Social Security Act [codified as 42 U.S.C. § 405(c)(2)(A)] shall, except as shall otherwise be specified under regulations of the Secretary [of the Treasury or his delegate], be used as the identifying number for such individual for purposes of this title [the Internal Revenue Code, title 26 of the United States Code].”[22]

The Internal Revenue Code also provides, when required by regulations prescribed by the Secretary [of the Treasury or his delegate]:

  • Inclusion in returns: Any person required under the authority of this title to make a return, statement, or other document shall include in such return, statement, or other document such identifying number as may be prescribed for securing proper identification of such person.
  • Furnishing number to other persons: Any person with respect to whom a return, statement, or other document is required under the authority of this title to be made by another person or whose identifying number is required to be shown on a return of another person shall furnish to such other person such identifying number as may be prescribed for securing his proper identification.[23]
  • According to U.S. Treasury regulations, any person who, after October 31, 1962, works as an employee for wages subject to Social Security taxes, Medicare taxes, or U.S. federal income tax withholdings is required to apply for “an account number” using “Form SS-5.”[24]

    A taxpayer who is not eligible to have a Social Security number must obtain an alternative Taxpayer Identification Number.

    Types of Social Security cards[edit]

    Three different types of Social Security cards are issued. The most common type contains the cardholder’s name and number. Such cards are issued to U.S. citizens and U.S. permanent residents. There are also two restricted types of Social Security cards:

    • One reads “not valid for employment.” Such cards cannot be used as proof of work authorization, and are not acceptable as a List C document on the I-9 form.
    • The other reads “valid for work only with DHS authorization”, or the older, “valid for work only with INS authorization.” These cards are issued to people who have temporary work authorization in the U.S. They can satisfy the I-9 requirement, if they are accompanied by a work authorization card.

    In 2004 Congress passed The Intelligence Reform and Terrorism Prevention Act; parts of which mandated that the Social Security Administration redesign the Social Security Number (SSN) Card to prevent forgery. From April 2006 through August 2007, Social Security Administration (SSA) and Government Printing Office (GPO) employees were assigned to redesign the Social Security Number Card to the specifications of the Interagency Task Force created by the Commissioner of Social Security in consultation with the Secretary of Homeland Security.

    The new SSN card design utilizes both covert and overt security features created by the SSA and GPO design teams.

    Identity theft[edit]

    Dog tag from World War II (possibly Army-Air Corps), labeled “P” for Protestant.

    Many citizens and privacy advocates are concerned about the disclosure and processing of Social Security numbers. Furthermore, researchers at Carnegie Mellon University have demonstrated an algorithm that uses publicly available personal information to reconstruct a given SSN.[25]

    The SSN is frequently used by those involved in identity theft, since it is interconnected with many other forms of identification, and because people asking for it treat it as an authenticator. Financial institutions generally require an SSN to set up bank accounts, credit cards, and loans—partly because they assume that no one except the person it was issued to knows it.

    Exacerbating the problem of using the Social Security number as an identifier is the fact that the Social Security card contains no biometric identifiers of any sort, making it essentially impossible to tell whether a person using a certain SSN truly belongs to someone without relying on other documentation (which may itself have been falsely procured through use of the fraudulent SSN). Congress has proposed federal laws that restrict the use of SSNs for identification and bans their use for a number of commercial purposes—e.g., rental applications.[26]

    The Internal Revenue Service (IRS) offers alternatives to SSNs in some places where providing untrusted parties with identification numbers is essential. Tax return preparers must obtain and use a Preparer Tax Identification Number (PTIN) to include on their client’s tax returns (as part of signature requirements). Day care services have tax benefits, and even a sole proprietor should give parents an EIN (employer identification number) to use on their tax return.

    The Social Security Administration has suggested that, if asked to provide his or her Social Security number, a citizen should ask which law requires its use.[27] In accordance with §7213 of the 9/11 Commission Implementation Act of 2004 and 20 C.F.R. 422.103(e)(2), the number of replacement Social Security cards per person is generally limited to three per calendar year and ten in a lifetime.[27]

    Identity confusion has also occurred because of the use of local Social Security numbers by the Federated States of Micronesia, the Republic of the Marshall Islands, and the Republic of Palau, whose numbers overlap with those of residents of New Hampshire and Maine.[28]

    Replacement numbers[edit]

    A person can request a new Social Security number, but only under certain conditions;[29]

    • Where sequential numbers assigned to members of the same family are causing problems.
    • In the event of duplicates having been issued.
    • In cases where the person has been a victim of domestic violence or harassment, and there is a clear need to change their number for their personal safety.[30]
    • When a person has been a victim of identity theft, and their Social Security number continues to be problematic.
    • Where a person has a demonstrable religious objection to a number (such as certain Christians being averse to the number 666).

    For all of these conditions, credible third-party evidence such as a restraining order or police report, is required.


    The Social Security number is a nine-digit number in the format “AAA-GG-SSSS”.[31] The number is divided into three parts: the first three digits, known as the area number because they were formerly assigned by geographical region; the middle two digits, known as the group number; and the final four digits, known as the serial number.

    On June 25, 2011, the SSA changed the SSN assignment process to “SSN randomization”.[32] SSN randomization affected the SSN assignment process in the following ways:

  • It eliminated the geographical significance of the first three digits of the SSN, referred to as the area number, by no longer allocating specific numbers by state for assignment to individuals.
  • It eliminated the significance of the highest group number assigned for each area number, and, as a result, the High Group List is frozen in time and can be used for validation of only those SSNs issued prior to the randomization implementation date (see section “Valid SSNs”).
  • Previously unassigned area numbers have been introduced for assignment, excluding area numbers 000, 666 and 900–99.
  • Because Individual Taxpayer Identification Numbers (ITINs) are issued by the Internal Revenue Service (IRS), they were not affected by this SSA change.

    Historical structure[edit]

    Prior to the 2011 randomization process, the first three digits or area number were assigned by geographical region. Prior to 1973, cards were issued in local Social Security offices around the country and the area number represented the office code where the card was issued. This did not necessarily have to be in the area where the applicant lived, since a person could apply for their card in any Social Security office. Beginning in 1973, when the SSA began assigning SSNs and issuing cards centrally from Baltimore, the area number was assigned based on the ZIP Code in the mailing address provided on the application for the original Social Security card. The applicant’s mailing address did not have to be the same as their place of residence. Thus, the area number did not necessarily represent the state of residence of the applicant regardless of whether the card was issued prior to, or after, 1973.

    Generally, numbers were assigned beginning in the northeast and moving south and westward, so that people applying from addresses on the east coast had the lowest numbers and those on the west coast had the highest numbers. As the areas assigned to a locality were exhausted, new areas from the pool were assigned, so some states had noncontiguous groups of numbers.

    The middle two digits or group number range from 01 to 99. Even before SSN randomization, the group numbers were not assigned consecutively within an area. Instead, for administrative reasons, group numbers were issued in the following order:[33]

  • odd numbers from 01 through 09.
  • even numbers from 10 through 98.
  • even numbers from 02 through 08.
  • odd numbers from 11 through 99.
  • As an example, group number 98 would be issued before 11.

    The last four digits are serial numbers. Before SSN randomization took effect, they represented a straight numerical sequence of digits from 0001 to 9999 within the group.

    Valid SSNs[edit]

    Prior to June 25, 2011, a valid SSN could not have an area number between 734 and 749, or above 772, the highest area number the Social Security Administration had allocated. Effective June 25, 2011, the SSA assigns SSNs randomly and allows for the assignment of area numbers between 734 and 749 and above 772 through the 800s.[34] This should not be confused with Tax Identification Numbers (TINs), which include additional area numbers.[35]

    Some special numbers are never allocated:

    • Numbers with all zeros in any digit group (000-##-####, ###-00-####, ###-##-0000).[36][37]
    • Numbers with 666 or 900–999 (Individual Taxpayer Identification Number) in the first digit group.[36]

    Until 2011, the SSA published the last group number used for each area number.[38] Since group numbers were allocated in a regular pattern, it was possible to identify an unissued SSN that contained an invalid group number. Now numbers are assigned randomly, and fraudulent SSNs are not easily detectable with publicly available information. Many online services, however, provide SSN validation.

    Unlike many similar numbers, no check digit is included.

    Exhaustion and re-use[edit]

    The Social Security Administration does not reuse Social Security numbers. It has issued over 450 million since the start of the program, and at a use rate of about 5.5 million per year. It says it has enough to last several generations without reuse or changing the number of digits.[39] However, there have been instances where multiple individuals have been inadvertently assigned the same Social Security number.[40]

    SSNs used in advertising[edit]

    The promotional Social Security card as distributed by the F.W. Woolworth Company

    Some SSNs used in advertising have rendered those numbers invalid. One famous instance of this occurred in 1938 when the E. H. Ferree Company in Lockport, New York, decided to promote its product by showing how a Social Security card would fit into its wallets. A sample card, used for display purposes, was placed in each wallet, which was sold by Woolworth and other department stores across the country; the wallet manufacturer’s vice president and treasurer Douglas Patterson used the actual SSN of his secretary, Hilda Schrader Whitcher.

    Even though the card was printed in red (the real card is printed in blue) and had “Specimen” printed across the front, many people used Whitcher’s SSN as their own. The Social Security Administration’s account of the incident also claims that the fake card was half the size of a real card, despite a miniature card’s being useless for its purpose and despite Whitcher’s holding two cards of apparently identical size in the accompanying photograph. Over time, the number that appeared (078-05-1120) has been claimed by a total of over 40,000 people as their own.[41] The SSA initiated an advertising campaign stating that it was incorrect to use the number (Hilda Whitcher was issued a new SSN). However, the number was found to be in use by 12 individuals as late as 1977.[41]

    More recently, Todd Davis distributed his SSN in advertisements for his company’s LifeLock identity theft protection service, which allowed his identity to be stolen over a dozen times.[42][43]

    List of Social Security Area Numbers[edit]

    List showing the geographical location of the first three digits of the social security numbers assigned in the United States and its territories since 1973. Repeated numbers indicate that they’ve been transferred to another location or they’re shared by more than one location.

    The above table is only valid for SSN issued before June 2011. On June 25, 2011, the SSA changed the SSN assignment process to “SSN randomization”.[45] SSN randomization affects the SSN assignment process. Among its changes, it eliminates the geographical significance of the first three digits of the SSN, previously referred to as the Area Number, by no longer allocating the Area Numbers for assignment to individuals in specific states. The table above is based on out-of-date information. Numbers in the range of 650-699 most certainly have been issued (see related comment on the Talk page).

    See also[edit]

    • Cadastro de Pessoas Físicas
    • Death Master File
    • Feature creep
    • INSEE code
    • Italian fiscal code card
    • Kennitala
    • National Insurance number
    • National Registration Identity Card
    • NHI Number
    • NIE Number
    • Permanent account number
    • Personally identifiable information
    • PESEL
    • PPS number
    • Social Insurance Number
    • Tax file number
    • Uniform civil number
    • Unique Population Registry Code


  • ^ “The Story of the Social Security Number”. Retrieved 2012-08-20. 
  • ^ a b Kouri, Jim (March 9, 2005). “Social Security Cards: De Facto National Identification”. American Chronicle. Archived from the original on June 29, 2012. 
  • ^ 20 C.F.R. 422.103(b)
  • ^ “Social Security Online”. Retrieved 2011-02-23. 
  • ^ “The First Social Security Number and the Lowest Number”. Social Security History. United States Social Security Administration. Retrieved July 27, 2015. 
  • ^ “First Applicant on Pension List”. Ogden Standard Examiner. Ogden, Utah. December 2, 1936. p. 8. 
  • ^ Long, Wayne S. (Spring 1993). “Social Security Numbers Issued: A 20-Year Review” (PDF). Social Security Journal. 56 (1): 82. Retrieved 23 July 2017. 
  • ^ Goldberg, Jack (1993). “A strategy for assembling samples of adult twin pairs in the United States”. Statistics in Medicine. 12 (18): 1693–1702. doi:10.1002/sim.4780121805. Retrieved 23 July 2017. 
  • ^ “Tax Reform Act of 1986”. Social Security History. United States Social Security Administration. Retrieved July 27, 2015.  (“Unlike the PIN the SSN is not universally assigned, nor is it issued at birth. In the U.S., assignment of the SSN occurs traditionally when an individual joins the workforce, usually as a teenager. The age at SSN issuance, however, has been declining for decades” and recent changes in the tax law now require that all infants claimed as dependants must have an SSN by one year of age.”)
  • ^ Jeffrey B. Liebman (December 2000). “Who Are the Ineligible EITC Recipients?”. National Tax Journal. 53: 1165–1186. 
  • ^ “Social Security Number Chronology”. Social Security Administration. 
  • ^ a b “Social Security Numbers For Children”. Social Security Administration. 
  • ^ “National Personnel Records Center”. National Archives. 
  • ^ “DOD removes SSAN from ID cards”. 
  • ^ “The Amish & Social Security”. Retrieved 2011-02-23. 
  • ^ “Amish reject giving Social Security numbers to get licenses”. The Chippewa Herald. August 30, 1999. Retrieved August 23, 2012. 
  • ^ “Version History”. Social Security History. United States Social Security Administration. Archived from the original on June 29, 2012. Retrieved July 27, 2015. 
  • ^ Pear, Robert (July 26, 1998). “The Nation; Not for Identification Purposes (Just Kidding)”. The New York Times. Retrieved May 23, 2010. 
  • ^ “Social Security Number Not Required”. 2008-04-29. Retrieved 2011-02-23. 
  • ^ Charles H. Mullen, Associate Commissioner (March 18, 1998), Letter to Mr. Scott McDonald (PDF), Office of Public Enquiries, Social Security Administration, retrieved July 27, 2015 
  • ^ “Can I refuse to give my Social Security number to a private business?”. Frequently Asked Questions. United States Social Security Administration. May 18, 2018. 
  • ^ 26 U.S.C. § 6109(d).
  • ^ See 26 U.S.C. § 6109(a).
  • ^ See 26 C.F.R. sec. 31.6011(b)-2(a)(1)(ii).
  • ^ “New algorithm guesses SSNs using date and place of birth”. Ars Technica. July 2009. 
  • ^ Broache, Anne. “Congress may slap restrictions on SSN use – CNET News”. Archived from the original on 2012-07-11. Retrieved 2011-02-23. 
  • ^ a b “Your Social Security Number And Card, “How can I protect my Social Security number?””. Social Security Administration. 
  • ^ Meyer, Bill (August 2009). “How many Americans’ Social Security numbers were officially duplicated for Pacific islanders?”. The Plain Dealer. Retrieved 2012-08-20. 
  • ^ “Social Security: Frequently Asked Questions – Can I change my Social Security number?”. Social Security Administration. Retrieved 22 May 2017. 
  • ^ “New Numbers for Domestic Violence Victims” (PDF). Social Security Administration. Retrieved 22 May 2017. 
  • ^ Social Security Administration. “The SSN Numbering Scheme”. Retrieved December 25, 2010. 
  • ^ “Social Security Number Randomization”. Retrieved 2011-02-23. 
  • ^ “The SSN Numbering Scheme”. Retrieved 2011-02-23. 
  • ^ “List of valid area numbers”. Social Security Administration. Retrieved October 14, 2015. 
  • ^ “Taxpayer Identification Numbers (TIN)”. Internal Revenue Service. 
  • ^ a b “Which Social Security numbers are invalid?”. Social Security Administration. Retrieved October 14, 2015. 
  • ^ “RM 10201.035 Invalid Social Security Numbers (SSNs)”. Program Operations Manual System (POMS). United States Social Security Administration. June 23, 2011. Retrieved October 14, 2015. 
  • ^ “List currently allocated group numbers for each area number”. Social Security Administration. Retrieved October 14, 2015. 
  • ^ “Q20: Are Social Security numbers reused after a person dies?”. Frequently Asked Questions. United States Social Security Administration. Retrieved July 27, 2015. 
  • ^ “A tale of two women: same birthday, same Social Security number, same big-data mess”. PC World. Retrieved November 12, 2015. 
  • ^ a b “The story of the most misused number of all time…” Social Security Administration. 
  • ^ Zetter, Kim (May 18, 2010). “LifeLock CEO’s Identity Stolen 13 Times”. Wired. 
  • ^ Vijayan, Jaikumar (May 19, 2010). “LifeLock CEO said to be victim of identity theft 13 times”. ComputerWorld. 
  • ^
  • ^ “Social Security Number Randomization”. Retrieved 2011-02-23. 
  • External links[edit]

    • Social Security Administration
    • Social Security Death Index Database listing over 85 million SSNs, all of which entered the public domain upon the death of their owners
    • Replacing a Lost or Stolen Social Security Card
    • The Woolworth Card: The SSN 078-05-1120 has been claimed by thousands of people since the late 1930s
    • Social Security Cards Issued by Woolworth: “The story of the most misused number of all time”
    • Complete list of area number groups from the Social Security Administration
    • Social Security Administration’s FAQ for Social Security Numbers
    • Social Security card application
    • Hearing on Removing Social Security Numbers from Medicare Cards: Joint Hearing before the Subcommittee on Social Security and Subcommittee on Health of the Committee on Ways and Means, U.S. House of Representatives, One Hundred Twelfth Congress, Second Session, August 1, 2012
    • Look up public information about Social Security Numbers derived from the SSN enumeration pattern prior to 2011
    • Carolyn Puckett (2009). “The Story of the Social Security Number”. Social Security Bulletin. 69 (2).  (PDF version)

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